example of a lab report hypothesis

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How to Write a Lab Report – with Example/Template

April 11, 2024

Perhaps you’re in the midst of your challenging AP chemistry class in high school, or perhaps college you’re enrolled in biology , chemistry , or physics at university. At some point, you will likely be asked to write a lab report. Sometimes, your teacher or professor will give you specific instructions for how to format and write your lab report, and if so, use that. In case you’re left to your own devices, here are some guidelines you might find useful. Continue reading for the main elements of a lab report, followed by a detailed description of the more writing-heavy parts (with a lab report example/lab report template). Lastly, we’ve included an outline that can help get you started.

What is a lab report?

A lab report is an overview of your experiment. Essentially, it explains what you did in the experiment and how it went. Most lab reports end up being 5-10 pages long (graphs or other images included), though the length depends on the experiment. Here are some brief explanations of the essential parts of a lab report:

Title : The title says, in the most straightforward way possible, what you did in the experiment. Often, the title looks something like, “Effects of ____ on _____.” Sometimes, a lab report also requires a title page, which includes your name (and the names of any lab partners), your instructor’s name, and the date of the experiment.

Abstract : This is a short description of key findings of the experiment so that a potential reader could get an idea of the experiment before even beginning.

Introduction : This is comprised of one or several paragraphs summarizing the purpose of the lab. The introduction usually includes the hypothesis, as well as some background information.

Lab Report Example (Continued)

Materials : Perhaps the simplest part of your lab report, this is where you list everything needed for the completion of your experiment.

Methods : This is where you describe your experimental procedure. The section provides necessary information for someone who would want to replicate your study. In paragraph form, write out your methods in chronological order, though avoid excessive detail.

Data : Here, you should document what happened in the experiment, step-by-step. This section often includes graphs and tables with data, as well as descriptions of patterns and trends. You do not need to interpret all of the data in this section, but you can describe trends or patterns, and state which findings are interesting and/or significant.

Discussion of results : This is the overview of your findings from the experiment, with an explanation of how they pertain to your hypothesis, as well as any anomalies or errors.

Conclusion : Your conclusion will sum up the results of your experiment, as well as their significance. Sometimes, conclusions also suggest future studies.

Sources : Often in APA style , you should list all texts that helped you with your experiment. Make sure to include course readings, outside sources, and other experiments that you may have used to design your own.

How to write the abstract

The abstract is the experiment stated “in a nutshell”: the procedure, results, and a few key words. The purpose of the academic abstract is to help a potential reader get an idea of the experiment so they can decide whether to read the full paper. So, make sure your abstract is as clear and direct as possible, and under 200 words (though word count varies).

When writing an abstract for a scientific lab report, we recommend covering the following points:

• Background : Why was this experiment conducted?
• Objectives : What problem is being addressed by this experiment?
• Methods : How was the study designed and conducted?
• Results : What results were found and what do they mean?
• Conclusion : Were the results expected? Is this problem better understood now than before? If so, how?

How to write the introduction

The introduction is another summary, of sorts, so it could be easy to confuse the introduction with the abstract. While the abstract tends to be around 200 words summarizing the entire study, the introduction can be longer if necessary, covering background information on the study, what you aim to accomplish, and your hypothesis. Unlike the abstract (or the conclusion), the introduction does not need to state the results of the experiment.

Here is a possible order with which you can organize your lab report introduction:

• Intro of the intro : Plainly state what your study is doing.
• Background : Provide a brief overview of the topic being studied. This could include key terms and definitions. This should not be an extensive literature review, but rather, a window into the most relevant topics a reader would need to understand in order to understand your research.
• Importance : Now, what are the gaps in existing research? Given the background you just provided, what questions do you still have that led you to conduct this experiment? Are you clarifying conflicting results? Are you undertaking a new area of research altogether?
• Prediction: The plants placed by the window will grow faster than plants placed in the dark corner.
• Hypothesis: Basil plants placed in direct sunlight for 2 hours per day grow at a higher rate than basil plants placed in direct sunlight for 30 minutes per day.
• How you test your hypothesis : This is an opportunity to briefly state how you go about your experiment, but this is not the time to get into specific details about your methods (save this for your results section). Keep this part down to one sentence, and voila! You have your introduction.

How to write a discussion section

Here, we’re skipping ahead to the next writing-heavy section, which will directly follow the numeric data of your experiment. The discussion includes any calculations and interpretations based on this data. In other words, it says, “Now that we have the data, why should we care?”  This section asks, how does this data sit in relation to the hypothesis? Does it prove your hypothesis or disprove it? The discussion is also a good place to mention any mistakes that were made during the experiment, and ways you would improve the experiment if you were to repeat it. Like the other written sections, it should be as concise as possible.

Here is a list of points to cover in your lab report discussion:

• Weaker statement: These findings prove that basil plants grow more quickly in the sunlight.
• Stronger statement: These findings support the hypothesis that basil plants placed in direct sunlight grow at a higher rate than basil plants given less direct sunlight.
• Factors influencing results : This is also an opportunity to mention any anomalies, errors, or inconsistencies in your data. Perhaps when you tested the first round of basil plants, the days were sunnier than the others. Perhaps one of the basil pots broke mid-experiment so it needed to be replanted, which affected your results. If you were to repeat the study, how would you change it so that the results were more consistent?
• Implications : How do your results contribute to existing research? Here, refer back to the gaps in research that you mentioned in your introduction. Do these results fill these gaps as you hoped?
• Questions for future research : Based on this, how might your results contribute to future research? What are the next steps, or the next experiments on this topic? Make sure this does not become too broad—keep it to the scope of this project.

How to write a lab report conclusion

This is your opportunity to briefly remind the reader of your findings and finish strong. Your conclusion should be especially concise (avoid going into detail on findings or introducing new information).

Here are elements to include as you write your conclusion, in about 1-2 sentences each:

• Restate your goals : What was the main question of your experiment? Refer back to your introduction—similar language is okay.
• Restate your methods : In a sentence or so, how did you go about your experiment?
• Key findings : Briefly summarize your main results, but avoid going into detail.
• Limitations : What about your experiment was less-than-ideal, and how could you improve upon the experiment in future studies?
• Significance and future research : Why is your research important? What are the logical next-steps for studying this topic?

Template for beginning your lab report

Here is a compiled outline from the bullet points in these sections above, with some examples based on the (overly-simplistic) basil growth experiment. Hopefully this will be useful as you begin your lab report.

1) Title (ex: Effects of Sunlight on Basil Plant Growth )

2) Abstract (approx. 200 words)

• Background ( This experiment looks at… )
• Objectives ( It aims to contribute to research on…)
• Methods ( It does so through a process of…. )
• Results (Findings supported the hypothesis that… )
• Conclusion (These results contribute to a wider understanding about…)

3) Introduction (approx. 1-2 paragraphs)

• Intro ( This experiment looks at… )
• Background ( Past studies on basil plant growth and sunlight have found…)
• Importance ( This experiment will contribute to these past studies by…)
• Hypothesis ( Basil plants placed in direct sunlight for 2 hours per day grow at a higher rate than basil plants placed in direct sunlight for 30 minutes per day.)
• How you will test your hypothesis ( This hypothesis will be tested by a process of…)

4) Materials (list form) (ex: pots, soil, seeds, tables/stands, water, light source )

5) Methods (approx. 1-2 paragraphs) (ex: 10 basil plants were measured throughout a span of…)

6) Data (brief description and figures) (ex: These charts demonstrate a pattern that the basil plants placed in direct sunlight…)

7) Discussion (approx. 2-3 paragraphs)

• Support or reject hypothesis ( These findings support the hypothesis that basil plants placed in direct sunlight grow at a higher rate than basil plants given less direct sunlight.)
• Factors that influenced your results ( Outside factors that could have altered the results include…)
• Implications ( These results contribute to current research on basil plant growth and sunlight because…)
• Questions for further research ( Next steps for this research could include…)
• Restate your goals ( In summary, the goal of this experiment was to measure…)
• Restate your methods ( This hypothesis was tested by…)
• Key findings ( The findings supported the hypothesis because…)
• Limitations ( Although, certain elements were overlooked, including…)
• Significance and future research ( This experiment presents possibilities of future research contributions, such as…)
• Sources (approx. 1 page, usually in APA style)

Final thoughts – Lab Report Example

Hopefully, these descriptions have helped as you write your next lab report. Remember that different instructors may have different preferences for structure and format, so make sure to double-check when you receive your assignment. All in all, make sure to keep your scientific lab report concise, focused, honest, and organized. Good luck!

For more reading on coursework success, check out the following articles:

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• How to Write a Strong Hypothesis | Guide & Examples

How to Write a Strong Hypothesis | Guide & Examples

Published on 6 May 2022 by Shona McCombes .

A hypothesis is a statement that can be tested by scientific research. If you want to test a relationship between two or more variables, you need to write hypotheses before you start your experiment or data collection.

Table of contents

What is a hypothesis, developing a hypothesis (with example), hypothesis examples, frequently asked questions about writing hypotheses.

A hypothesis states your predictions about what your research will find. It is a tentative answer to your research question that has not yet been tested. For some research projects, you might have to write several hypotheses that address different aspects of your research question.

A hypothesis is not just a guess – it should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations, and statistical analysis of data).

Variables in hypotheses

Hypotheses propose a relationship between two or more variables . An independent variable is something the researcher changes or controls. A dependent variable is something the researcher observes and measures.

In this example, the independent variable is exposure to the sun – the assumed cause . The dependent variable is the level of happiness – the assumed effect .

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Step 1: ask a question.

Writing a hypothesis begins with a research question that you want to answer. The question should be focused, specific, and researchable within the constraints of your project.

Step 2: Do some preliminary research

Your initial answer to the question should be based on what is already known about the topic. Look for theories and previous studies to help you form educated assumptions about what your research will find.

At this stage, you might construct a conceptual framework to identify which variables you will study and what you think the relationships are between them. Sometimes, you’ll have to operationalise more complex constructs.

Step 3: Formulate your hypothesis

Now you should have some idea of what you expect to find. Write your initial answer to the question in a clear, concise sentence.

Step 4: Refine your hypothesis

You need to make sure your hypothesis is specific and testable. There are various ways of phrasing a hypothesis, but all the terms you use should have clear definitions, and the hypothesis should contain:

• The relevant variables
• The specific group being studied
• The predicted outcome of the experiment or analysis

Step 5: Phrase your hypothesis in three ways

To identify the variables, you can write a simple prediction in if … then form. The first part of the sentence states the independent variable and the second part states the dependent variable.

In academic research, hypotheses are more commonly phrased in terms of correlations or effects, where you directly state the predicted relationship between variables.

If you are comparing two groups, the hypothesis can state what difference you expect to find between them.

Step 6. Write a null hypothesis

If your research involves statistical hypothesis testing , you will also have to write a null hypothesis. The null hypothesis is the default position that there is no association between the variables. The null hypothesis is written as H 0 , while the alternative hypothesis is H 1 or H a .

Hypothesis testing is a formal procedure for investigating our ideas about the world using statistics. It is used by scientists to test specific predictions, called hypotheses , by calculating how likely it is that a pattern or relationship between variables could have arisen by chance.

A hypothesis is not just a guess. It should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations, and statistical analysis of data).

A research hypothesis is your proposed answer to your research question. The research hypothesis usually includes an explanation (‘ x affects y because …’).

A statistical hypothesis, on the other hand, is a mathematical statement about a population parameter. Statistical hypotheses always come in pairs: the null and alternative hypotheses. In a well-designed study , the statistical hypotheses correspond logically to the research hypothesis.

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How to Write a Lab Report

Lab Reports Describe Your Experiment

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Lab reports are an essential part of all laboratory courses and usually a significant part of your grade. If your instructor gives you an outline for how to write a lab report, use that. Some instructors require a lab report to be included in a lab notebook , while others will request a separate report. Here's a format for a lab report you can use if you aren't sure what to write or need an explanation of what to include in the different parts of the report.

A lab report is how you explain what you did in ​your experiment, what you learned, and what the results meant.

Lab Report Essentials

Not all lab reports have title pages, but if your instructor wants one, it would be a single page that states:​

• The title of the experiment.
• Your name and the names of any lab partners.
• Your instructor's name.
• The date the lab was performed or the date the report was submitted.

The title says what you did. It should be brief (aim for ten words or less) and describe the main point of the experiment or investigation. An example of a title would be: "Effects of Ultraviolet Light on Borax Crystal Growth Rate". If you can, begin your title using a keyword rather than an article like "The" or "A".

Introduction or Purpose

Usually, the introduction is one paragraph that explains the objectives or purpose of the lab. In one sentence, state the hypothesis. Sometimes an introduction may contain background information, briefly summarize how the experiment was performed, state the findings of the experiment, and list the conclusions of the investigation. Even if you don't write a whole introduction, you need to state the purpose of the experiment, or why you did it. This would be where you state your hypothesis .

List everything needed to complete your experiment.

Describe the steps you completed during your investigation. This is your procedure. Be sufficiently detailed that anyone could read this section and duplicate your experiment. Write it as if you were giving direction for someone else to do the lab. It may be helpful to provide a figure to diagram your experimental setup.

Numerical data obtained from your procedure usually presented as a table. Data encompasses what you recorded when you conducted the experiment. It's just the facts, not any interpretation of what they mean.

Describe in words what the data means. Sometimes the Results section is combined with the Discussion.

Discussion or Analysis

The Data section contains numbers; the Analysis section contains any calculations you made based on those numbers. This is where you interpret the data and determine whether or not a hypothesis was accepted. This is also where you would discuss any mistakes you might have made while conducting the investigation. You may wish to describe ways the study might have been improved.

Conclusions

Most of the time the conclusion is a single paragraph that sums up what happened in the experiment, whether your hypothesis was accepted or rejected, and what this means.

Figures and Graphs

Graphs and figures must both be labeled with a descriptive title. Label the axes on a graph, being sure to include units of measurement. The independent variable is on the X-axis, the dependent variable (the one you are measuring) is on the Y-axis. Be sure to refer to figures and graphs in the text of your report: the first figure is Figure 1, the second figure is Figure 2, etc.

If your research was based on someone else's work or if you cited facts that require documentation, then you should list these references.

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Writing Lab Reports

Writing lab reports follows a straightforward and structured procedure. It is important to recognize that each part of a lab report is important, so take the time to complete each carefully. A lab report is broken down into eight sections: title, abstract, introduction, methods and materials, results, discussion, conclusion, and references. 

• Ex: "Determining the Free Chlorine Content of Pool Water"
• Abstracts are a summary of the experiment as a whole and should familiarize the reader with the purpose of the research. 
• Abstracts will always be written last, even though they are the first paragraph of a lab report. 
• Not all lab reports will require an abstract. However, they are often included in upper-level lab reports and should be studied carefully. 
• Why was the research done or experiment conducted?
• What problem is being addressed?
• What results were found?
• What are the meaning of the results?
• How is the problem better understood now than before, if at all?

Introduction

• The introduction of a lab report discusses the problem being studied and other theory that is relevant to understanding the findings. 
• The hypothesis of the experiment and the motivation for the research are stated in this section. 
• Write the introduction in your own words. Try not to copy from a lab manual or other guidelines. Instead, show comprehension of the experiment by briefly explaining the problem.

Methods and Materials

• Ex: pipette, graduated cylinder, 1.13mg of Na, 0.67mg Ag
• List the steps taken as they actually happened during the experiment, not as they were supposed to happen. 
• If written correctly, another researcher should be able to duplicate the experiment and get the same or very similar results. 
• The results show the data that was collected or found during the experiment. 
• Explain in words the data that was collected.
• Tables should be labeled numerically, as "Table 1", "Table 2", etc. Other figures should be labeled numerically as "Figure 1", "Figure 2", etc. 
• Calculations to understand the data can also be presented in the results. 
• The discussion section is one of the most important parts of the lab report. It analyzes the results of the experiment and is a discussion of the data. 
• If any results are unexpected, explain why they are unexpected and how they did or did not effect the data obtained. 
• Analyze the strengths and weaknesses of the design of the experiment and compare your results to other similar experiments.
• If there are any experimental errors, analyze them.
• Explain your results and discuss them using relevant terms and theories.
• What do the results indicate?
• What is the significance of the results?
• Are there any gaps in knowledge?
• Are there any new questions that have been raised?
• The conclusion is a summation of the experiment. It should clearly and concisely state what was learned and its importance.
• If there is future work that needs to be done, it can be explained in the conclusion.
• If using any outside sources to support a claim or explain background information, those sources must be cited in the references section of the lab report. 
• In the event that no outside sources are used, the references section may be left out. 

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Scientific Reports

What this handout is about.

This handout provides a general guide to writing reports about scientific research you’ve performed. In addition to describing the conventional rules about the format and content of a lab report, we’ll also attempt to convey why these rules exist, so you’ll get a clearer, more dependable idea of how to approach this writing situation. Readers of this handout may also find our handout on writing in the sciences useful.

Background and pre-writing

Why do we write research reports.

You did an experiment or study for your science class, and now you have to write it up for your teacher to review. You feel that you understood the background sufficiently, designed and completed the study effectively, obtained useful data, and can use those data to draw conclusions about a scientific process or principle. But how exactly do you write all that? What is your teacher expecting to see?

To take some of the guesswork out of answering these questions, try to think beyond the classroom setting. In fact, you and your teacher are both part of a scientific community, and the people who participate in this community tend to share the same values. As long as you understand and respect these values, your writing will likely meet the expectations of your audience—including your teacher.

So why are you writing this research report? The practical answer is “Because the teacher assigned it,” but that’s classroom thinking. Generally speaking, people investigating some scientific hypothesis have a responsibility to the rest of the scientific world to report their findings, particularly if these findings add to or contradict previous ideas. The people reading such reports have two primary goals:

• They want to gather the information presented.
• They want to know that the findings are legitimate.

Your job as a writer, then, is to fulfill these two goals.

How do I do that?

Good question. Here is the basic format scientists have designed for research reports:

• Introduction

Methods and Materials

This format, sometimes called “IMRAD,” may take slightly different shapes depending on the discipline or audience; some ask you to include an abstract or separate section for the hypothesis, or call the Discussion section “Conclusions,” or change the order of the sections (some professional and academic journals require the Methods section to appear last). Overall, however, the IMRAD format was devised to represent a textual version of the scientific method.

The scientific method, you’ll probably recall, involves developing a hypothesis, testing it, and deciding whether your findings support the hypothesis. In essence, the format for a research report in the sciences mirrors the scientific method but fleshes out the process a little. Below, you’ll find a table that shows how each written section fits into the scientific method and what additional information it offers the reader.

Thinking of your research report as based on the scientific method, but elaborated in the ways described above, may help you to meet your audience’s expectations successfully. We’re going to proceed by explicitly connecting each section of the lab report to the scientific method, then explaining why and how you need to elaborate that section.

Although this handout takes each section in the order in which it should be presented in the final report, you may for practical reasons decide to compose sections in another order. For example, many writers find that composing their Methods and Results before the other sections helps to clarify their idea of the experiment or study as a whole. You might consider using each assignment to practice different approaches to drafting the report, to find the order that works best for you.

What should I do before drafting the lab report?

The best way to prepare to write the lab report is to make sure that you fully understand everything you need to about the experiment. Obviously, if you don’t quite know what went on during the lab, you’re going to find it difficult to explain the lab satisfactorily to someone else. To make sure you know enough to write the report, complete the following steps:

• What are we going to do in this lab? (That is, what’s the procedure?)
• Why are we going to do it that way?
• What are we hoping to learn from this experiment?
• Why would we benefit from this knowledge?
• Consult your lab supervisor as you perform the lab. If you don’t know how to answer one of the questions above, for example, your lab supervisor will probably be able to explain it to you (or, at least, help you figure it out).
• Plan the steps of the experiment carefully with your lab partners. The less you rush, the more likely it is that you’ll perform the experiment correctly and record your findings accurately. Also, take some time to think about the best way to organize the data before you have to start putting numbers down. If you can design a table to account for the data, that will tend to work much better than jotting results down hurriedly on a scrap piece of paper.
• Record the data carefully so you get them right. You won’t be able to trust your conclusions if you have the wrong data, and your readers will know you messed up if the other three people in your group have “97 degrees” and you have “87.”
• Consult with your lab partners about everything you do. Lab groups often make one of two mistakes: two people do all the work while two have a nice chat, or everybody works together until the group finishes gathering the raw data, then scrams outta there. Collaborate with your partners, even when the experiment is “over.” What trends did you observe? Was the hypothesis supported? Did you all get the same results? What kind of figure should you use to represent your findings? The whole group can work together to answer these questions.
• Consider your audience. You may believe that audience is a non-issue: it’s your lab TA, right? Well, yes—but again, think beyond the classroom. If you write with only your lab instructor in mind, you may omit material that is crucial to a complete understanding of your experiment, because you assume the instructor knows all that stuff already. As a result, you may receive a lower grade, since your TA won’t be sure that you understand all the principles at work. Try to write towards a student in the same course but a different lab section. That student will have a fair degree of scientific expertise but won’t know much about your experiment particularly. Alternatively, you could envision yourself five years from now, after the reading and lectures for this course have faded a bit. What would you remember, and what would you need explained more clearly (as a refresher)?

Once you’ve completed these steps as you perform the experiment, you’ll be in a good position to draft an effective lab report.

Introductions

How do i write a strong introduction.

For the purposes of this handout, we’ll consider the Introduction to contain four basic elements: the purpose, the scientific literature relevant to the subject, the hypothesis, and the reasons you believed your hypothesis viable. Let’s start by going through each element of the Introduction to clarify what it covers and why it’s important. Then we can formulate a logical organizational strategy for the section.

The inclusion of the purpose (sometimes called the objective) of the experiment often confuses writers. The biggest misconception is that the purpose is the same as the hypothesis. Not quite. We’ll get to hypotheses in a minute, but basically they provide some indication of what you expect the experiment to show. The purpose is broader, and deals more with what you expect to gain through the experiment. In a professional setting, the hypothesis might have something to do with how cells react to a certain kind of genetic manipulation, but the purpose of the experiment is to learn more about potential cancer treatments. Undergraduate reports don’t often have this wide-ranging a goal, but you should still try to maintain the distinction between your hypothesis and your purpose. In a solubility experiment, for example, your hypothesis might talk about the relationship between temperature and the rate of solubility, but the purpose is probably to learn more about some specific scientific principle underlying the process of solubility.

For starters, most people say that you should write out your working hypothesis before you perform the experiment or study. Many beginning science students neglect to do so and find themselves struggling to remember precisely which variables were involved in the process or in what way the researchers felt that they were related. Write your hypothesis down as you develop it—you’ll be glad you did.

As for the form a hypothesis should take, it’s best not to be too fancy or complicated; an inventive style isn’t nearly so important as clarity here. There’s nothing wrong with beginning your hypothesis with the phrase, “It was hypothesized that . . .” Be as specific as you can about the relationship between the different objects of your study. In other words, explain that when term A changes, term B changes in this particular way. Readers of scientific writing are rarely content with the idea that a relationship between two terms exists—they want to know what that relationship entails.

Not a hypothesis:

“It was hypothesized that there is a significant relationship between the temperature of a solvent and the rate at which a solute dissolves.”

Hypothesis:

“It was hypothesized that as the temperature of a solvent increases, the rate at which a solute will dissolve in that solvent increases.”

Put more technically, most hypotheses contain both an independent and a dependent variable. The independent variable is what you manipulate to test the reaction; the dependent variable is what changes as a result of your manipulation. In the example above, the independent variable is the temperature of the solvent, and the dependent variable is the rate of solubility. Be sure that your hypothesis includes both variables.

Justify your hypothesis

You need to do more than tell your readers what your hypothesis is; you also need to assure them that this hypothesis was reasonable, given the circumstances. In other words, use the Introduction to explain that you didn’t just pluck your hypothesis out of thin air. (If you did pluck it out of thin air, your problems with your report will probably extend beyond using the appropriate format.) If you posit that a particular relationship exists between the independent and the dependent variable, what led you to believe your “guess” might be supported by evidence?

Scientists often refer to this type of justification as “motivating” the hypothesis, in the sense that something propelled them to make that prediction. Often, motivation includes what we already know—or rather, what scientists generally accept as true (see “Background/previous research” below). But you can also motivate your hypothesis by relying on logic or on your own observations. If you’re trying to decide which solutes will dissolve more rapidly in a solvent at increased temperatures, you might remember that some solids are meant to dissolve in hot water (e.g., bouillon cubes) and some are used for a function precisely because they withstand higher temperatures (they make saucepans out of something). Or you can think about whether you’ve noticed sugar dissolving more rapidly in your glass of iced tea or in your cup of coffee. Even such basic, outside-the-lab observations can help you justify your hypothesis as reasonable.

Background/previous research

This part of the Introduction demonstrates to the reader your awareness of how you’re building on other scientists’ work. If you think of the scientific community as engaging in a series of conversations about various topics, then you’ll recognize that the relevant background material will alert the reader to which conversation you want to enter.

Generally speaking, authors writing journal articles use the background for slightly different purposes than do students completing assignments. Because readers of academic journals tend to be professionals in the field, authors explain the background in order to permit readers to evaluate the study’s pertinence for their own work. You, on the other hand, write toward a much narrower audience—your peers in the course or your lab instructor—and so you must demonstrate that you understand the context for the (presumably assigned) experiment or study you’ve completed. For example, if your professor has been talking about polarity during lectures, and you’re doing a solubility experiment, you might try to connect the polarity of a solid to its relative solubility in certain solvents. In any event, both professional researchers and undergraduates need to connect the background material overtly to their own work.

Organization of this section

Most of the time, writers begin by stating the purpose or objectives of their own work, which establishes for the reader’s benefit the “nature and scope of the problem investigated” (Day 1994). Once you have expressed your purpose, you should then find it easier to move from the general purpose, to relevant material on the subject, to your hypothesis. In abbreviated form, an Introduction section might look like this:

“The purpose of the experiment was to test conventional ideas about solubility in the laboratory [purpose] . . . According to Whitecoat and Labrat (1999), at higher temperatures the molecules of solvents move more quickly . . . We know from the class lecture that molecules moving at higher rates of speed collide with one another more often and thus break down more easily [background material/motivation] . . . Thus, it was hypothesized that as the temperature of a solvent increases, the rate at which a solute will dissolve in that solvent increases [hypothesis].”

Again—these are guidelines, not commandments. Some writers and readers prefer different structures for the Introduction. The one above merely illustrates a common approach to organizing material.

How do I write a strong Materials and Methods section?

As with any piece of writing, your Methods section will succeed only if it fulfills its readers’ expectations, so you need to be clear in your own mind about the purpose of this section. Let’s review the purpose as we described it above: in this section, you want to describe in detail how you tested the hypothesis you developed and also to clarify the rationale for your procedure. In science, it’s not sufficient merely to design and carry out an experiment. Ultimately, others must be able to verify your findings, so your experiment must be reproducible, to the extent that other researchers can follow the same procedure and obtain the same (or similar) results.

Here’s a real-world example of the importance of reproducibility. In 1989, physicists Stanley Pons and Martin Fleischman announced that they had discovered “cold fusion,” a way of producing excess heat and power without the nuclear radiation that accompanies “hot fusion.” Such a discovery could have great ramifications for the industrial production of energy, so these findings created a great deal of interest. When other scientists tried to duplicate the experiment, however, they didn’t achieve the same results, and as a result many wrote off the conclusions as unjustified (or worse, a hoax). To this day, the viability of cold fusion is debated within the scientific community, even though an increasing number of researchers believe it possible. So when you write your Methods section, keep in mind that you need to describe your experiment well enough to allow others to replicate it exactly.

With these goals in mind, let’s consider how to write an effective Methods section in terms of content, structure, and style.

Sometimes the hardest thing about writing this section isn’t what you should talk about, but what you shouldn’t talk about. Writers often want to include the results of their experiment, because they measured and recorded the results during the course of the experiment. But such data should be reserved for the Results section. In the Methods section, you can write that you recorded the results, or how you recorded the results (e.g., in a table), but you shouldn’t write what the results were—not yet. Here, you’re merely stating exactly how you went about testing your hypothesis. As you draft your Methods section, ask yourself the following questions:

• How much detail? Be precise in providing details, but stay relevant. Ask yourself, “Would it make any difference if this piece were a different size or made from a different material?” If not, you probably don’t need to get too specific. If so, you should give as many details as necessary to prevent this experiment from going awry if someone else tries to carry it out. Probably the most crucial detail is measurement; you should always quantify anything you can, such as time elapsed, temperature, mass, volume, etc.
• Rationale: Be sure that as you’re relating your actions during the experiment, you explain your rationale for the protocol you developed. If you capped a test tube immediately after adding a solute to a solvent, why did you do that? (That’s really two questions: why did you cap it, and why did you cap it immediately?) In a professional setting, writers provide their rationale as a way to explain their thinking to potential critics. On one hand, of course, that’s your motivation for talking about protocol, too. On the other hand, since in practical terms you’re also writing to your teacher (who’s seeking to evaluate how well you comprehend the principles of the experiment), explaining the rationale indicates that you understand the reasons for conducting the experiment in that way, and that you’re not just following orders. Critical thinking is crucial—robots don’t make good scientists.
• Control: Most experiments will include a control, which is a means of comparing experimental results. (Sometimes you’ll need to have more than one control, depending on the number of hypotheses you want to test.) The control is exactly the same as the other items you’re testing, except that you don’t manipulate the independent variable-the condition you’re altering to check the effect on the dependent variable. For example, if you’re testing solubility rates at increased temperatures, your control would be a solution that you didn’t heat at all; that way, you’ll see how quickly the solute dissolves “naturally” (i.e., without manipulation), and you’ll have a point of reference against which to compare the solutions you did heat.

Describe the control in the Methods section. Two things are especially important in writing about the control: identify the control as a control, and explain what you’re controlling for. Here is an example:

“As a control for the temperature change, we placed the same amount of solute in the same amount of solvent, and let the solution stand for five minutes without heating it.”

Structure and style

Organization is especially important in the Methods section of a lab report because readers must understand your experimental procedure completely. Many writers are surprised by the difficulty of conveying what they did during the experiment, since after all they’re only reporting an event, but it’s often tricky to present this information in a coherent way. There’s a fairly standard structure you can use to guide you, and following the conventions for style can help clarify your points.

• Subsections: Occasionally, researchers use subsections to report their procedure when the following circumstances apply: 1) if they’ve used a great many materials; 2) if the procedure is unusually complicated; 3) if they’ve developed a procedure that won’t be familiar to many of their readers. Because these conditions rarely apply to the experiments you’ll perform in class, most undergraduate lab reports won’t require you to use subsections. In fact, many guides to writing lab reports suggest that you try to limit your Methods section to a single paragraph.
• Narrative structure: Think of this section as telling a story about a group of people and the experiment they performed. Describe what you did in the order in which you did it. You may have heard the old joke centered on the line, “Disconnect the red wire, but only after disconnecting the green wire,” where the person reading the directions blows everything to kingdom come because the directions weren’t in order. We’re used to reading about events chronologically, and so your readers will generally understand what you did if you present that information in the same way. Also, since the Methods section does generally appear as a narrative (story), you want to avoid the “recipe” approach: “First, take a clean, dry 100 ml test tube from the rack. Next, add 50 ml of distilled water.” You should be reporting what did happen, not telling the reader how to perform the experiment: “50 ml of distilled water was poured into a clean, dry 100 ml test tube.” Hint: most of the time, the recipe approach comes from copying down the steps of the procedure from your lab manual, so you may want to draft the Methods section initially without consulting your manual. Later, of course, you can go back and fill in any part of the procedure you inadvertently overlooked.
• Past tense: Remember that you’re describing what happened, so you should use past tense to refer to everything you did during the experiment. Writers are often tempted to use the imperative (“Add 5 g of the solid to the solution”) because that’s how their lab manuals are worded; less frequently, they use present tense (“5 g of the solid are added to the solution”). Instead, remember that you’re talking about an event which happened at a particular time in the past, and which has already ended by the time you start writing, so simple past tense will be appropriate in this section (“5 g of the solid were added to the solution” or “We added 5 g of the solid to the solution”).
• Active: We heated the solution to 80°C. (The subject, “we,” performs the action, heating.)
• Passive: The solution was heated to 80°C. (The subject, “solution,” doesn’t do the heating–it is acted upon, not acting.)

Increasingly, especially in the social sciences, using first person and active voice is acceptable in scientific reports. Most readers find that this style of writing conveys information more clearly and concisely. This rhetorical choice thus brings two scientific values into conflict: objectivity versus clarity. Since the scientific community hasn’t reached a consensus about which style it prefers, you may want to ask your lab instructor.

How do I write a strong Results section?

Here’s a paradox for you. The Results section is often both the shortest (yay!) and most important (uh-oh!) part of your report. Your Materials and Methods section shows how you obtained the results, and your Discussion section explores the significance of the results, so clearly the Results section forms the backbone of the lab report. This section provides the most critical information about your experiment: the data that allow you to discuss how your hypothesis was or wasn’t supported. But it doesn’t provide anything else, which explains why this section is generally shorter than the others.

Before you write this section, look at all the data you collected to figure out what relates significantly to your hypothesis. You’ll want to highlight this material in your Results section. Resist the urge to include every bit of data you collected, since perhaps not all are relevant. Also, don’t try to draw conclusions about the results—save them for the Discussion section. In this section, you’re reporting facts. Nothing your readers can dispute should appear in the Results section.

Most Results sections feature three distinct parts: text, tables, and figures. Let’s consider each part one at a time.

This should be a short paragraph, generally just a few lines, that describes the results you obtained from your experiment. In a relatively simple experiment, one that doesn’t produce a lot of data for you to repeat, the text can represent the entire Results section. Don’t feel that you need to include lots of extraneous detail to compensate for a short (but effective) text; your readers appreciate discrimination more than your ability to recite facts. In a more complex experiment, you may want to use tables and/or figures to help guide your readers toward the most important information you gathered. In that event, you’ll need to refer to each table or figure directly, where appropriate:

“Table 1 lists the rates of solubility for each substance”

“Solubility increased as the temperature of the solution increased (see Figure 1).”

If you do use tables or figures, make sure that you don’t present the same material in both the text and the tables/figures, since in essence you’ll just repeat yourself, probably annoying your readers with the redundancy of your statements.

Feel free to describe trends that emerge as you examine the data. Although identifying trends requires some judgment on your part and so may not feel like factual reporting, no one can deny that these trends do exist, and so they properly belong in the Results section. Example:

“Heating the solution increased the rate of solubility of polar solids by 45% but had no effect on the rate of solubility in solutions containing non-polar solids.”

This point isn’t debatable—you’re just pointing out what the data show.

As in the Materials and Methods section, you want to refer to your data in the past tense, because the events you recorded have already occurred and have finished occurring. In the example above, note the use of “increased” and “had,” rather than “increases” and “has.” (You don’t know from your experiment that heating always increases the solubility of polar solids, but it did that time.)

You shouldn’t put information in the table that also appears in the text. You also shouldn’t use a table to present irrelevant data, just to show you did collect these data during the experiment. Tables are good for some purposes and situations, but not others, so whether and how you’ll use tables depends upon what you need them to accomplish.

Tables are useful ways to show variation in data, but not to present a great deal of unchanging measurements. If you’re dealing with a scientific phenomenon that occurs only within a certain range of temperatures, for example, you don’t need to use a table to show that the phenomenon didn’t occur at any of the other temperatures. How useful is this table?

As you can probably see, no solubility was observed until the trial temperature reached 50°C, a fact that the text part of the Results section could easily convey. The table could then be limited to what happened at 50°C and higher, thus better illustrating the differences in solubility rates when solubility did occur.

As a rule, try not to use a table to describe any experimental event you can cover in one sentence of text. Here’s an example of an unnecessary table from How to Write and Publish a Scientific Paper , by Robert A. Day:

As Day notes, all the information in this table can be summarized in one sentence: “S. griseus, S. coelicolor, S. everycolor, and S. rainbowenski grew under aerobic conditions, whereas S. nocolor and S. greenicus required anaerobic conditions.” Most readers won’t find the table clearer than that one sentence.

When you do have reason to tabulate material, pay attention to the clarity and readability of the format you use. Here are a few tips:

• Number your table. Then, when you refer to the table in the text, use that number to tell your readers which table they can review to clarify the material.
• Give your table a title. This title should be descriptive enough to communicate the contents of the table, but not so long that it becomes difficult to follow. The titles in the sample tables above are acceptable.
• Arrange your table so that readers read vertically, not horizontally. For the most part, this rule means that you should construct your table so that like elements read down, not across. Think about what you want your readers to compare, and put that information in the column (up and down) rather than in the row (across). Usually, the point of comparison will be the numerical data you collect, so especially make sure you have columns of numbers, not rows.Here’s an example of how drastically this decision affects the readability of your table (from A Short Guide to Writing about Chemistry , by Herbert Beall and John Trimbur). Look at this table, which presents the relevant data in horizontal rows:

It’s a little tough to see the trends that the author presumably wants to present in this table. Compare this table, in which the data appear vertically:

The second table shows how putting like elements in a vertical column makes for easier reading. In this case, the like elements are the measurements of length and height, over five trials–not, as in the first table, the length and height measurements for each trial.

• Make sure to include units of measurement in the tables. Readers might be able to guess that you measured something in millimeters, but don’t make them try.
• Don’t use vertical lines as part of the format for your table. This convention exists because journals prefer not to have to reproduce these lines because the tables then become more expensive to print. Even though it’s fairly unlikely that you’ll be sending your Biology 11 lab report to Science for publication, your readers still have this expectation. Consequently, if you use the table-drawing option in your word-processing software, choose the option that doesn’t rely on a “grid” format (which includes vertical lines).

How do I include figures in my report?

Although tables can be useful ways of showing trends in the results you obtained, figures (i.e., illustrations) can do an even better job of emphasizing such trends. Lab report writers often use graphic representations of the data they collected to provide their readers with a literal picture of how the experiment went.

When should you use a figure?

Remember the circumstances under which you don’t need a table: when you don’t have a great deal of data or when the data you have don’t vary a lot. Under the same conditions, you would probably forgo the figure as well, since the figure would be unlikely to provide your readers with an additional perspective. Scientists really don’t like their time wasted, so they tend not to respond favorably to redundancy.

If you’re trying to decide between using a table and creating a figure to present your material, consider the following a rule of thumb. The strength of a table lies in its ability to supply large amounts of exact data, whereas the strength of a figure is its dramatic illustration of important trends within the experiment. If you feel that your readers won’t get the full impact of the results you obtained just by looking at the numbers, then a figure might be appropriate.

Of course, an undergraduate class may expect you to create a figure for your lab experiment, if only to make sure that you can do so effectively. If this is the case, then don’t worry about whether to use figures or not—concentrate instead on how best to accomplish your task.

Figures can include maps, photographs, pen-and-ink drawings, flow charts, bar graphs, and section graphs (“pie charts”). But the most common figure by far, especially for undergraduates, is the line graph, so we’ll focus on that type in this handout.

At the undergraduate level, you can often draw and label your graphs by hand, provided that the result is clear, legible, and drawn to scale. Computer technology has, however, made creating line graphs a lot easier. Most word-processing software has a number of functions for transferring data into graph form; many scientists have found Microsoft Excel, for example, a helpful tool in graphing results. If you plan on pursuing a career in the sciences, it may be well worth your while to learn to use a similar program.

Computers can’t, however, decide for you how your graph really works; you have to know how to design your graph to meet your readers’ expectations. Here are some of these expectations:

• Keep it as simple as possible. You may be tempted to signal the complexity of the information you gathered by trying to design a graph that accounts for that complexity. But remember the purpose of your graph: to dramatize your results in a manner that’s easy to see and grasp. Try not to make the reader stare at the graph for a half hour to find the important line among the mass of other lines. For maximum effectiveness, limit yourself to three to five lines per graph; if you have more data to demonstrate, use a set of graphs to account for it, rather than trying to cram it all into a single figure.
• Plot the independent variable on the horizontal (x) axis and the dependent variable on the vertical (y) axis. Remember that the independent variable is the condition that you manipulated during the experiment and the dependent variable is the condition that you measured to see if it changed along with the independent variable. Placing the variables along their respective axes is mostly just a convention, but since your readers are accustomed to viewing graphs in this way, you’re better off not challenging the convention in your report.
• Label each axis carefully, and be especially careful to include units of measure. You need to make sure that your readers understand perfectly well what your graph indicates.
• Number and title your graphs. As with tables, the title of the graph should be informative but concise, and you should refer to your graph by number in the text (e.g., “Figure 1 shows the increase in the solubility rate as a function of temperature”).
• Many editors of professional scientific journals prefer that writers distinguish the lines in their graphs by attaching a symbol to them, usually a geometric shape (triangle, square, etc.), and using that symbol throughout the curve of the line. Generally, readers have a hard time distinguishing dotted lines from dot-dash lines from straight lines, so you should consider staying away from this system. Editors don’t usually like different-colored lines within a graph because colors are difficult and expensive to reproduce; colors may, however, be great for your purposes, as long as you’re not planning to submit your paper to Nature. Use your discretion—try to employ whichever technique dramatizes the results most effectively.
• Try to gather data at regular intervals, so the plot points on your graph aren’t too far apart. You can’t be sure of the arc you should draw between the plot points if the points are located at the far corners of the graph; over a fifteen-minute interval, perhaps the change occurred in the first or last thirty seconds of that period (in which case your straight-line connection between the points is misleading).
• If you’re worried that you didn’t collect data at sufficiently regular intervals during your experiment, go ahead and connect the points with a straight line, but you may want to examine this problem as part of your Discussion section.
• Make your graph large enough so that everything is legible and clearly demarcated, but not so large that it either overwhelms the rest of the Results section or provides a far greater range than you need to illustrate your point. If, for example, the seedlings of your plant grew only 15 mm during the trial, you don’t need to construct a graph that accounts for 100 mm of growth. The lines in your graph should more or less fill the space created by the axes; if you see that your data is confined to the lower left portion of the graph, you should probably re-adjust your scale.
• If you create a set of graphs, make them the same size and format, including all the verbal and visual codes (captions, symbols, scale, etc.). You want to be as consistent as possible in your illustrations, so that your readers can easily make the comparisons you’re trying to get them to see.

How do I write a strong Discussion section?

The discussion section is probably the least formalized part of the report, in that you can’t really apply the same structure to every type of experiment. In simple terms, here you tell your readers what to make of the Results you obtained. If you have done the Results part well, your readers should already recognize the trends in the data and have a fairly clear idea of whether your hypothesis was supported. Because the Results can seem so self-explanatory, many students find it difficult to know what material to add in this last section.

Basically, the Discussion contains several parts, in no particular order, but roughly moving from specific (i.e., related to your experiment only) to general (how your findings fit in the larger scientific community). In this section, you will, as a rule, need to:

Explain whether the data support your hypothesis

• Acknowledge any anomalous data or deviations from what you expected

Derive conclusions, based on your findings, about the process you’re studying

• Relate your findings to earlier work in the same area (if you can)

Explore the theoretical and/or practical implications of your findings

Let’s look at some dos and don’ts for each of these objectives.

This statement is usually a good way to begin the Discussion, since you can’t effectively speak about the larger scientific value of your study until you’ve figured out the particulars of this experiment. You might begin this part of the Discussion by explicitly stating the relationships or correlations your data indicate between the independent and dependent variables. Then you can show more clearly why you believe your hypothesis was or was not supported. For example, if you tested solubility at various temperatures, you could start this section by noting that the rates of solubility increased as the temperature increased. If your initial hypothesis surmised that temperature change would not affect solubility, you would then say something like,

“The hypothesis that temperature change would not affect solubility was not supported by the data.”

Note: Students tend to view labs as practical tests of undeniable scientific truths. As a result, you may want to say that the hypothesis was “proved” or “disproved” or that it was “correct” or “incorrect.” These terms, however, reflect a degree of certainty that you as a scientist aren’t supposed to have. Remember, you’re testing a theory with a procedure that lasts only a few hours and relies on only a few trials, which severely compromises your ability to be sure about the “truth” you see. Words like “supported,” “indicated,” and “suggested” are more acceptable ways to evaluate your hypothesis.

Also, recognize that saying whether the data supported your hypothesis or not involves making a claim to be defended. As such, you need to show the readers that this claim is warranted by the evidence. Make sure that you’re very explicit about the relationship between the evidence and the conclusions you draw from it. This process is difficult for many writers because we don’t often justify conclusions in our regular lives. For example, you might nudge your friend at a party and whisper, “That guy’s drunk,” and once your friend lays eyes on the person in question, she might readily agree. In a scientific paper, by contrast, you would need to defend your claim more thoroughly by pointing to data such as slurred words, unsteady gait, and the lampshade-as-hat. In addition to pointing out these details, you would also need to show how (according to previous studies) these signs are consistent with inebriation, especially if they occur in conjunction with one another. To put it another way, tell your readers exactly how you got from point A (was the hypothesis supported?) to point B (yes/no).

Acknowledge any anomalous data, or deviations from what you expected

You need to take these exceptions and divergences into account, so that you qualify your conclusions sufficiently. For obvious reasons, your readers will doubt your authority if you (deliberately or inadvertently) overlook a key piece of data that doesn’t square with your perspective on what occurred. In a more philosophical sense, once you’ve ignored evidence that contradicts your claims, you’ve departed from the scientific method. The urge to “tidy up” the experiment is often strong, but if you give in to it you’re no longer performing good science.

Sometimes after you’ve performed a study or experiment, you realize that some part of the methods you used to test your hypothesis was flawed. In that case, it’s OK to suggest that if you had the chance to conduct your test again, you might change the design in this or that specific way in order to avoid such and such a problem. The key to making this approach work, though, is to be very precise about the weakness in your experiment, why and how you think that weakness might have affected your data, and how you would alter your protocol to eliminate—or limit the effects of—that weakness. Often, inexperienced researchers and writers feel the need to account for “wrong” data (remember, there’s no such animal), and so they speculate wildly about what might have screwed things up. These speculations include such factors as the unusually hot temperature in the room, or the possibility that their lab partners read the meters wrong, or the potentially defective equipment. These explanations are what scientists call “cop-outs,” or “lame”; don’t indicate that the experiment had a weakness unless you’re fairly certain that a) it really occurred and b) you can explain reasonably well how that weakness affected your results.

If, for example, your hypothesis dealt with the changes in solubility at different temperatures, then try to figure out what you can rationally say about the process of solubility more generally. If you’re doing an undergraduate lab, chances are that the lab will connect in some way to the material you’ve been covering either in lecture or in your reading, so you might choose to return to these resources as a way to help you think clearly about the process as a whole.

This part of the Discussion section is another place where you need to make sure that you’re not overreaching. Again, nothing you’ve found in one study would remotely allow you to claim that you now “know” something, or that something isn’t “true,” or that your experiment “confirmed” some principle or other. Hesitate before you go out on a limb—it’s dangerous! Use less absolutely conclusive language, including such words as “suggest,” “indicate,” “correspond,” “possibly,” “challenge,” etc.

Relate your findings to previous work in the field (if possible)

We’ve been talking about how to show that you belong in a particular community (such as biologists or anthropologists) by writing within conventions that they recognize and accept. Another is to try to identify a conversation going on among members of that community, and use your work to contribute to that conversation. In a larger philosophical sense, scientists can’t fully understand the value of their research unless they have some sense of the context that provoked and nourished it. That is, you have to recognize what’s new about your project (potentially, anyway) and how it benefits the wider body of scientific knowledge. On a more pragmatic level, especially for undergraduates, connecting your lab work to previous research will demonstrate to the TA that you see the big picture. You have an opportunity, in the Discussion section, to distinguish yourself from the students in your class who aren’t thinking beyond the barest facts of the study. Capitalize on this opportunity by putting your own work in context.

If you’re just beginning to work in the natural sciences (as a first-year biology or chemistry student, say), most likely the work you’ll be doing has already been performed and re-performed to a satisfactory degree. Hence, you could probably point to a similar experiment or study and compare/contrast your results and conclusions. More advanced work may deal with an issue that is somewhat less “resolved,” and so previous research may take the form of an ongoing debate, and you can use your own work to weigh in on that debate. If, for example, researchers are hotly disputing the value of herbal remedies for the common cold, and the results of your study suggest that Echinacea diminishes the symptoms but not the actual presence of the cold, then you might want to take some time in the Discussion section to recapitulate the specifics of the dispute as it relates to Echinacea as an herbal remedy. (Consider that you have probably already written in the Introduction about this debate as background research.)

This information is often the best way to end your Discussion (and, for all intents and purposes, the report). In argumentative writing generally, you want to use your closing words to convey the main point of your writing. This main point can be primarily theoretical (“Now that you understand this information, you’re in a better position to understand this larger issue”) or primarily practical (“You can use this information to take such and such an action”). In either case, the concluding statements help the reader to comprehend the significance of your project and your decision to write about it.

Since a lab report is argumentative—after all, you’re investigating a claim, and judging the legitimacy of that claim by generating and collecting evidence—it’s often a good idea to end your report with the same technique for establishing your main point. If you want to go the theoretical route, you might talk about the consequences your study has for the field or phenomenon you’re investigating. To return to the examples regarding solubility, you could end by reflecting on what your work on solubility as a function of temperature tells us (potentially) about solubility in general. (Some folks consider this type of exploration “pure” as opposed to “applied” science, although these labels can be problematic.) If you want to go the practical route, you could end by speculating about the medical, institutional, or commercial implications of your findings—in other words, answer the question, “What can this study help people to do?” In either case, you’re going to make your readers’ experience more satisfying, by helping them see why they spent their time learning what you had to teach them.

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

American Psychological Association. 2010. Publication Manual of the American Psychological Association . 6th ed. Washington, DC: American Psychological Association.

Beall, Herbert, and John Trimbur. 2001. A Short Guide to Writing About Chemistry , 2nd ed. New York: Longman.

Blum, Deborah, and Mary Knudson. 1997. A Field Guide for Science Writers: The Official Guide of the National Association of Science Writers . New York: Oxford University Press.

Booth, Wayne C., Gregory G. Colomb, Joseph M. Williams, Joseph Bizup, and William T. FitzGerald. 2016. The Craft of Research , 4th ed. Chicago: University of Chicago Press.

Briscoe, Mary Helen. 1996. Preparing Scientific Illustrations: A Guide to Better Posters, Presentations, and Publications , 2nd ed. New York: Springer-Verlag.

Council of Science Editors. 2014. Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers , 8th ed. Chicago & London: University of Chicago Press.

Davis, Martha. 2012. Scientific Papers and Presentations , 3rd ed. London: Academic Press.

Day, Robert A. 1994. How to Write and Publish a Scientific Paper , 4th ed. Phoenix: Oryx Press.

Porush, David. 1995. A Short Guide to Writing About Science . New York: Longman.

Williams, Joseph, and Joseph Bizup. 2017. Style: Lessons in Clarity and Grace , 12th ed. Boston: Pearson.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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Lab Report Format – How to Write a Laboratory Report

A science laboratory experiment isn’t truly complete until you’ve written the lab report. You may have taken excellent notes in your laboratory notebook, but it isn’t the same as a lab report. The lab report format is designed to present experimental results so they can be shared with others. A well-written report explains what you did, why you did it, and what you learned. It should also generate reader interest, potentially leading to peer-reviewed publication and funding.

Sections of a Lab Report

There is no one lab report format. The format and sections might be specified by your instructor or employer. What really matters is covering all of the important information.

Label the sections (except the title). Use bold face type for the title and headings. The order is:

You may or may not be expected to provide a title page. If it is required, the title page includes the title of the experiment, the names of the researchers, the name of the institution, and the date.

The title describes the experiment. Don’t start it with an article (e.g., the, an, a) because it messes up databases and isn’t necessary. For example, a good title might be, “Effect of Increasing Glucose Concentration on Danio rerio Egg Hatching Rates.” Use title case and italicize the scientific names of any species.

Introduction

Sometimes the introduction is broken into separate sections. Otherwise, it’s written as a narrative that includes the following information:

• State the purpose of the experiment.
• State the hypothesis.
• Review earlier work on the subject. Refer to previous studies. Cover the background so a reader understands what is known about a subject and what you hope to learn that is new.
• Describe your approach to answering a question or solving a problem. Include a theory or equation, if appropriate.

This section describes experimental design. Identify the parameter you changed ( independent variable ) and the one you measured ( dependent variable ). Describe the equipment and set-up you used, materials, and methods. If a reader can’t picture the apparatus from your description, include a photograph or diagram. Sometimes this section is broken into “Materials” and “Methods.”

Your lab notebook contains all of the data you collected in the experiment. You aren’t expected to reproduce all of this in a lab report. Instead, provide labelled tables and graphs. The first figure is Figure 1, the second is Figure 2, etc. The first graph is Graph 1. Refer to figures and graphs by their figure number. For some experiments, you may need to include labelled photographs. Cite the results of any calculations you performed, such as slope and standard deviation. Discuss sources of error here, including instrument, standard, and random errors.

Discussion or Conclusions

While the “Results” section includes graphs and tables, the “Discussion” or “Conclusions” section focuses on what the results mean. This is where you state whether or not the objective of the experiment was met and what the outcome means.  Propose reasons for discrepancies between expected and actual outcomes. Finally, describe the next logical step in your research and ways you might improve on the experiment.

References or Bibliography

Did you build upon work conducted by someone else? Cite the work. Did you consult a paper relating to the experiment? Credit the author. If you’re unsure whether to cite a reference or not, a good rule of thumb is to include a reference for any fact not known to your audience. For some reports, it’s only necessary to list publications directly relating to your procedure and conclusions.

The Tone of a Lab Report

Lab reports should be informative, not entertaining. This isn’t the place for humor, sarcasm, or flowery prose. A lab report should be:

• Concise : Cover all the key points without getting crazy with the details.
• Objective : In the “Conclusions” section, you can propose possible explanations for your results. Otherwise, keep your opinions out of the report. Instead, present facts and an analysis based on logic and math.
• Critical : After presenting what you did, the report focuses on what the data means. Be on the lookout for sources of error and identify them. Use your understanding of error to determine how reliable your results are and gauge confidence in your conclusions.

Related Posts

Princeton Correspondents on Undergraduate Research

How to Write An Effective Lab Report

Whether you are in lab for general chemistry, independent work, or senior thesis, almost all lab experiments will be followed up with a lab report or paper. Although it should be relatively easy to write about an experiment you completed, this is often the most difficult part of lab work, especially when the results are unexpected. In this post, I will outline the components of a lab report while offering tips on how to write one.

Understand Your Experiments Thoroughly

Before you begin writing your draft, it is important that you understand your experiment, as this will help you decide what to include in your paper. When I wrote my first organic chemistry lab report, I rushed to begin answering the discussion questions only to realize halfway through that I had a major conceptual error. Because of this, I had to revise most of what I had written so far, which cost me a lot of time. Know what the purpose of the lab is, formulate the hypothesis, and begin to think about the results you are expecting. At this point, it is helpful to check in with your Lab TA, mentor, or principal investigator (PI) to ensure that you thoroughly understand your project. 

The abstract of your lab report will generally consist of a short summary of your entire report, typically in the same order as your report. Although this is the first section of your lab report, this should be the last section you write. Rather than trying to follow your entire report based on your abstract, it is easier if you write your report first before trying to summarize it.

Introduction and Background

The introduction and background of your report should establish the purpose of your experiment (what principles you are examining), your hypothesis (what you expect to see and why), and relevant findings from others in the field. You have likely done extensive reading about the project from textbooks, lecture notes, or scholarly articles. But as you write, only include background information that is relevant to your specific experiments. For instance, over the summer when I was still learning about metabolic engineering and its role in yeast cells, I read several articles detailing this process. However, a lot of this information was a very broad introduction to the field and not directly related to my project, so I decided not to include most of it. 

This section of the lab report should not contain a step-by-step procedure of your experiments, but rather enough details should be included so that someone else can understand and replicate what you did. From this section, the reader should understand how you tested your hypothesis and why you chose that method. Explain the different parts of your project, the variables being tested, and controls in your experiments. This section will validate the data presented by confirming that variables are being tested in a proper way.

You cannot change the data you collect from your experiments; thus the results section will be written for you. Your job is to present these results in appropriate tables and charts. Depending on the length of your project, you may have months of data from experiments or just a three-hour lab period worth of results. For example, for in-class lab reports, there is usually only one major experiment, so I include most of the data I collect in my lab report. But for longer projects such as summer internships, there are various preliminary experiments throughout, so I select the data to include. Although you cannot change the data, you must choose what is relevant to include in your report. Determine what is included in your report based on the goals and purpose of your project.

Discussion and Conclusion

In this section, you should analyze your results and relate your data back to your hypothesis. You should mention whether the results you obtained matched what was expected and the conclusions that can be drawn from this. For this section, you should talk about your data and conclusions with your lab mentors or TAs before you begin writing. As I mentioned above, by consulting with your mentors, you will avoid making large conceptual error that may take a long time to address.

There is no correct order for how to write a report, but it is generally easier to write some sections before others. For instance, because your results cannot be changed, it is easier to write the results section first. Likewise, because you also cannot change the methods you used in your experiment, it is helpful to write this section after writing your results. Although there are multiple ways to write and format a lab report or research paper, the goals of every report are the same: to describe what you did, your results, and why they are significant. As you write, keep your audience and these goals in mind.

— Saira Reyes, Engineering Correspondent

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27.5: Guide for writing a lab report

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Write a few short sentences briefly summarizing what you did, how you did it, what you found and whether anything went wrong in your experiment.

Describe relevant theories that relate to your experiment here, and the steps to carry out your procedure.

Consider the following questions:

• What are the relevant theories/principles that you used?
• What equations did you use? Show how you modeled your experiment.
• What materials, equipment and/or tools were necessary in making your measurements?
• Where was this experiment conducted?
• How did you make your measurements? How many times did you make them?
• How did you record your measurements?
• How did you determine and minimize the uncertainties in your measurements? Why did you choose to measure a specific quantity in a certain way?

It can be useful to predict the value (and uncertainty) that you expect to measure before conducting the measurement. You should report on this initial prediction in order to help you better understand the data from your experiment.

• Predict your measured values and uncertainties. How precise do you expect your measurements to be?
• What assumptions did you have to make to predict your results?
• Have these predictions influenced how you should approach your procedure? Make relevant adjustments to the procedure based on your predictions.

Data and Analysis

Present your data. Include relevant tables/graphs. Describe in detail how you analysed the data, including how you propagated uncertainties. If the data do not agree with your model prediction (or the prediction from your proposal), examine whether you can improve your model.

• How did you obtain the “final” measurement/value from your collected data?
• How did you propagate uncertainties? Why did you do it that way?
• What is the relative uncertainty on your value(s)?

Discussion and Conclusion

Summarize your findings, and address whether or not your model described the data. Discuss possible reasons why your measured value is not consisted with your model expectation (is it the model? is it the data?).

• Were there any systematic errors that you didn’t consider?
• Did you learn anything that you didn’t previously know? (eg. about the subject of your experiment, about the scientific method in general)
• If you could redo this experiment, what would you change (if anything)?

Guide for reviewing a lab report

Summarize your overall evaluation of the report in 2-3 sentences. Focus on the experiment’s method and its result. For example, “The authors dropped balls from different heights to determine the value of g”. You don’t need to go into the specific details, just give a high level summary of the report. If the report is unclear, specify this.

• Is the the procedure well thought-out, clearly and concisely described?
• Do you have sufficient information that you could repeat this experiment?
• Does the report clearly describe how different quantities were measured and how the uncertainties were determined?
• Does the report motivate why the specific procedure was chosen? (e.g. to minimize uncertainties).
• Does the experiment clearly state how uncertainties were propagated and how the data were analyzed?
• Do you believe their result to be scientifically valid?

Overall Rating of the Experiment

Give the report an overall score, based on the criteria described above. Use one of the following to rate the proposal and include a sentence to justify your choice.

• Satisfactory

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Writing the Experimental Report: Overview, Introductions, and Literature Reviews

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Experimental reports (also known as "lab reports") are reports of empirical research conducted by their authors. You should think of an experimental report as a "story" of your research in which you lead your readers through your experiment. As you are telling this story, you are crafting an argument about both the validity and reliability of your research, what your results mean, and how they fit into other previous work.

These next two sections provide an overview of the experimental report in APA format. Always check with your instructor, advisor, or journal editor for specific formatting guidelines.

General-specific-general format

Experimental reports follow a general to specific to general pattern. Your report will start off broadly in your introduction and discussion of the literature; the report narrows as it leads up to your specific hypotheses, methods, and results. Your discussion transitions from talking about your specific results to more general ramifications, future work, and trends relating to your research.

Experimental reports in APA format have a title page. Title page formatting is as follows:

• A running head and page number in the upper right corner (right aligned)
• A definition of running head in IN ALL CAPS below the running head (left aligned)
• Vertically and horizontally centered paper title, followed by author and affiliation

Please see our sample APA title page .

Crafting your story

Before you begin to write, carefully consider your purpose in writing: what is it that you discovered, would like to share, or would like to argue? You can see report writing as crafting a story about your research and your findings. Consider the following.

• What is the story you would like to tell?
• What literature best speaks to that story?
• How do your results tell the story?
• How can you discuss the story in broad terms?

During each section of your paper, you should be focusing on your story. Consider how each sentence, each paragraph, and each section contributes to your overall purpose in writing. Here is a description of one student's process.

Briel is writing an experimental report on her results from her experimental psychology lab class. She was interested in looking at the role gender plays in persuading individuals to take financial risks. After her data analysis, she finds that men are more easily persuaded by women to take financial risks and that men are generally willing to take more financial risks.

When Briel begins to write, she focuses her introduction on financial risk taking and gender, focusing on male behaviors. She then presents relevant literature on financial risk taking and gender that help illuminate her own study, but also help demonstrate the need for her own work. Her introduction ends with a study overview that directly leads from the literature review. Because she has already broadly introduced her study through her introduction and literature review, her readers can anticipate where she is going when she gets to her study overview. Her methods and results continue that story. Finally, her discussion concludes that story, discussing her findings, implications of her work, and the need for more research in the area of gender and financial risk taking.

The abstract gives a concise summary of the contents of the report.

• Abstracts should be brief (about 100 words)
• Abstracts should be self-contained and provide a complete picture of what the study is about
• Abstracts should be organized just like your experimental report—introduction, literature review, methods, results and discussion
• Abstracts should be written last during your drafting stage

Introduction

The introduction in an experimental article should follow a general to specific pattern, where you first introduce the problem generally and then provide a short overview of your own study. The introduction includes three parts: opening statements, literature review, and study overview.

Opening statements: Define the problem broadly in plain English and then lead into the literature review (this is the "general" part of the introduction). Your opening statements should already be setting the stage for the story you are going to tell.

Literature review: Discusses literature (previous studies) relevant to your current study in a concise manner. Keep your story in mind as you organize your lit review and as you choose what literature to include. The following are tips when writing your literature review.

• You should discuss studies that are directly related to your problem at hand and that logically lead to your own hypotheses.
• You do not need to provide a complete historical overview nor provide literature that is peripheral to your own study.
• Studies should be presented based on themes or concepts relevant to your research, not in a chronological format.
• You should also consider what gap in the literature your own research fills. What hasn't been examined? What does your work do that others have not?

Study overview: The literature review should lead directly into the last section of the introduction—your study overview. Your short overview should provide your hypotheses and briefly describe your method. The study overview functions as a transition to your methods section.

You should always give good, descriptive names to your hypotheses that you use consistently throughout your study. When you number hypotheses, readers must go back to your introduction to find them, which makes your piece more difficult to read. Using descriptive names reminds readers what your hypotheses were and allows for better overall flow.

In our example above, Briel had three different hypotheses based on previous literature. Her first hypothesis, the "masculine risk-taking hypothesis" was that men would be more willing to take financial risks overall. She clearly named her hypothesis in the study overview, and then referred back to it in her results and discussion sections.

Thais and Sanford (2000) recommend the following organization for introductions.

• Provide an introduction to your topic
• Provide a very concise overview of the literature
• State your hypotheses and how they connect to the literature
• Provide an overview of the methods for investigation used in your research

Bem (2006) provides the following rules of thumb for writing introductions.

• Write in plain English
• Take the time and space to introduce readers to your problem step-by-step; do not plunge them into the middle of the problem without an introduction
• Use examples to illustrate difficult or unfamiliar theories or concepts. The more complicated the concept or theory, the more important it is to have clear examples
• Open with a discussion about people and their behavior, not about psychologists and their research

Optional Lab Activities

Scientific method lab report.

The report should be typed and single spaced. See grading rubric at the end of this page for clarity on formatting.

Requirements

Should include Title (brief, concise, yet descriptive), your name, lab instructor’s name, and lab section (such as L14 or L24, etc.).

Note: this is a separate sheet

Body of Report

Identify the different sections of the body of the report with headings.

• The report should begin with a brief paragraph (complete sentences) that includes a statement of the problem and your hypothesis (remember your hypothesis should be written as a testable statement).
• What question are you trying to answer?
• Include any preliminary observations or background information about the subject (in this case the Alka-Seltzer tablet) such as what the tablet is used for, directions on packaging, personal experience you may have, etc. Be sure to cite any sources.
• Write a possible explanation/prediction for the problem/question you are asking.
• Make sure this possible explanation/prediction is a complete sentence and not a question.
• Make sure the statement is testable. In other words, can you perform an experiment that will either support or refute your prediction. If you cannot not think of a way to test your prediction, then it is not testable.
• Make a list (this does not need to be in paragraph form) of all  items used in the experiment and their quantities. Of the materials used, identify which are dependent and independent variables, constants (standardized variable) and control group (you will lose points if you do not identify all  dependent and independent variables, constants and controls) .
• Write at least one paragraph (complete sentences) which explains what you did in the experiment.
• Your procedure should be written so that anyone else could repeat the experiment. For instance, if you used hot water, how did you make the water hot and what temperature was it; if you chose salt water, what was the concentration of the salt water, etc. That means that even some of the most obvious steps need to be stated so there is no uncertainty.
• When designing the procedure, be sure to include replicating the experiment (trials) to ensure data is reproducible and valid.
• Write at least a paragraph (complete sentences) describing the results and observations of your experiment. Here you will compare results for control groups and experimental groups and not simply list the numbers.
• This section also includes both  a data table and graph to illustrate the results of you experiment. Be sure to include calculated averages of trials.
• All tables, graphs and charts should be labeled appropriately (a title, labels for x & y axis, legend etc.) so the reader will be able to understand the information presented.
• Write at least a paragraph restating your hypothesis and whether you accept or reject your hypothesis
• In this section, explain  why you accepted or rejected your hypothesis using data from the experiment . Include a brief summary of the data—averages, highest, lowest, etc., to help the reader understand your results and why you have come to particular conclusions.
• Discuss your thoughts about the possible reasons for your results (for example, if you chose salt water as a variable, give a possible reason why salt water, in particular, may have generated your results).
• Discuss possible errors that could have occurred in the collection of the data (experimental errors) and describe how these errors may have impacted the data.

Sample Report

This is a good lab report written for a different (and more complex experiment). You can use it as a model if you want.

Lab Report Grading Rubric

• Biology 101 Labs . Authored by : Lynette Hauser. Provided by : Tidewater Community College . Located at : http://www.tcc.edu/ . License : CC BY: Attribution

Writing Studio

Writing a lab report: introduction and discussion section guide.

In an effort to make our handouts more accessible, we have begun converting our PDF handouts to web pages. Download this page as a PDF:   Writing a Lab Report Return to Writing Studio Handouts

Part 1 (of 2): Introducing a Lab Report

The introduction of a lab report states the objective of the experiment and provides the reader with background information. State the topic of your report clearly and concisely (in one or two sentences). Provide background theory, previous research, or formulas the reader should know. Usually, an instructor does not want you to repeat whatever the lab manual says, but to show your understanding of the problem.

Questions an Effective Lab Report Introduction Should Answer

What is the problem.

Describe the problem investigated. Summarize relevant research to provide context, key terms, and concepts so that your reader can understand the experiment.

Why is it important?

Review relevant research to provide a rationale for the investigation. What conflict, unanswered question, untested population, or untried method in existing research does your experiment address? How will you challenge or extend the findings of other researchers?

What solution (or step toward a solution) do you propose?

Briefly describe your experiment : hypothesis , research question , general experimental design or method , and a justification of your method (if alternatives exist).

Tips on Composing Your Lab Report’s Introduction

• Move from the general to the specific – from a problem in research literature to the specifics of your experiment.
• Engage your reader – answer the questions: “What did I do?” “Why should my reader care?”
• Clarify the links between problem and solution, between question asked and research design, and between prior research and the specifics of your experiment.
• Be selective, not exhaustive, in choosing studies to cite and the amount of detail to include. In general, the more relevant an article is to your study, the more space it deserves and the later in the introduction it appears.
• Ask your instructor whether or not you should summarize results and/or conclusions in the Introduction.
• “The objective of the experiment was …”
• “The purpose of this report is …”
• “Bragg’s Law for diffraction is …”
• “The scanning electron microscope produces micrographs …”

Part 2 (of 2): Writing the “Discussion” Section of a Lab Report

The discussion is the most important part of your lab report, because here you show that you have not merely completed the experiment, but that you also understand its wider implications. The discussion section is reserved for putting experimental results in the context of the larger theory. Ask yourself: “What is the significance or meaning of the results?”

Elements of an Effective Discussion Section

What do the results indicate clearly? Based on your results, explain what you know with certainty and draw conclusions.

Interpretation

What is the significance of your results? What ambiguities exist? What are logical explanations for problems in the data? What questions might you raise about the methods used or the validity of the experiment? What can be logically deduced from your analysis?

Tips on the Discussion Section

1. explain your results in terms of theoretical issues..

How well has the theory been illustrated? What are the theoretical implications and practical applications of your results?

For each major result:

• Describe the patterns, principles, and relationships that your results show.
• Explain how your results relate to expectations and to literature cited in your Introduction. Explain any agreements, contradictions, or exceptions.
• Describe what additional research might resolve contradictions or explain exceptions.

2. Relate results to your experimental objective(s).

If you set out to identify an unknown metal by finding its lattice parameter and its atomic structure, be sure that you have identified the metal and its attributes.

3. Compare expected results with those obtained.

If there were differences, how can you account for them? Were the instruments able to measure precisely? Was the sample contaminated? Did calculated values take account of friction?

4. Analyze experimental error along with the strengths and limitations of the experiment’s design.

Were any errors avoidable? Were they the result of equipment?  If the flaws resulted from the experiment design, explain how the design might be improved. Consider, as well, the precision of the instruments that were used.

5. Compare your results to similar investigations.

In some cases, it is legitimate to compare outcomes with classmates, not in order to change your answer, but in order to look for and to account for or analyze any anomalies between the groups. Also, consider comparing your results to published scientific literature on the topic.

The “Introducing a Lab Report” guide was adapted from the University of Toronto Engineering Communications Centre and University of Wisconsin-Madison Writing Center.

The “Writing the Discussion Section of a Lab Report” resource was adapted from the University of Toronto Engineering Communications Centre and University of Wisconsin-Madison Writing Center.

Last revised: 07/2008 | Adapted for web delivery: 02/2021

In order to access certain content on this page, you may need to download Adobe Acrobat Reader or an equivalent PDF viewer software.

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Writing a scientific lab report is significantly different from writing for other classes like philosophy, English, and history. The most prominent form of writing in biology, chemistry, and environmental science is the lab report, which is a formally written description of results and discoveries found in an experiment. College lab reports should emulate and follow the same formats as reports found in scholarly journals, such as Nature , Cell , and The American Journal of Biochemistry .

Report Format

Title: The title says what you did. It should be brief (aim for ten words or less) and describe the main point of the experiment or investigation.

• Example:  Caffeine Increases Amylase Activity in the Mealworm ( Tenebrio molitar).
• If you can, begin your title using a keyword rather than an article like “The” or “A.”

Abstract: An abstract is a very concise summary of the purpose of the report, data presented, and major conclusions in about 100 - 200 words.  Abstracts are also commonly required for conference/presentation submissions because they summarize all of the essential materials necessary to understand the purpose of the experiment. They should consist of a background sentence , an introduction sentence , your hypothesis/purpose of the experiment, and a sentence about the results and what this means.

Introduction: The introduction of a lab report defines the subject of the report, provides background information and relevant studies, and outlines scientific purpose(s) and/or objective(s).

• The introduction is a place to provide the reader with necessary research on the topic and properly cite sources used.
• Summarizes the current literature on the topic including primary and secondary sources.
• Introduces the paper’s aims and scope.
• States the purpose of the experiment and the hypothesis.

Materials and Methods: The materials and methods section is a vital component of any formal lab report. This section of the report gives a detailed account of the procedure that was followed in completing the experiment as well as all important materials used. (This includes bacterial strains and species names in tests using living subjects.)

• Discusses the procedure of the experiment in as much detail as possible.
• Provides information about participants, apparatus, tools, substances, location of experiment, etc.
• For field studies, be sure to clearly explain where and when the work was done.
• It must be written so that anyone can use the methods section as instructions for exact replications.
• Don’t hesitate to use subheadings to organize these categories.
• Practice proper scientific writing forms. Be sure to use the proper abbreviations for units. Example: The 50mL sample was placed in a 5ºC room for 48hrs.

Results: The results section focuses on the findings, or data, in the experiment, as well as any statistical tests used to determine their significance.

• Concentrate on general trends and differences and not on trivial details.
• Summarize the data from the experiments without discussing their implications (This is where all the statistical analyses goes.)
• Organize data into tables, figures, graphs, photographs, etc.  Data in a table should not be duplicated in a graph or figure. Be sure to refer to tables and graphs in the written portion, for example, “Figure 1 shows that the activity....”
• Number and title all figures and tables separately, for example, Figure 1 and Table 1 and include a legend explaining symbols and abbreviations. Figures and graphs are labeled below the image while tables are labeled above.

  Discussion: The discussion section interprets the results, tying them back to background information and experiments performed by others in the past.This is also the area where further research opportunities shold be explored.

• Interpret the data; do not restate the results.
• Observations should also be noted in this section, especially anything unusual which may affect your results.

For example, if your bacteria was incubated at the wrong temperature or a piece of equipment failed mid-experiment, these should be noted in the results section.

• Relate results to existing theories and knowledge.This can tie back to your introduction section because of the background you provided.
• Explain the logic that allows you to accept or reject your original hypotheses.
• Include suggestions for improving your techniques or design, or clarify areas of doubt for further research.

Acknowledgements and References: A references list should be compiled at the end of the report citing any works that were used to support the paper. Additionally, an acknowledgements section should be included to acknowledge research advisors/ partners, any group or person providing funding for the research and anyone outside the authors who contributed to the paper or research.

General Tips

• In scientific papers, passive voice is perfectly acceptable. On the other hand, using “I” or “we” is not.

          Incorrect: We found that caffeine increased amylase levels in Tenebrio molitar.  Correct: It was discovered that caffeine increased amylase levels in Tenebrio molitar.   

• It is expected that you use as much formal (bland) language and scientific terminology as you can. There should be no emphasis placed on “expressing yourself” or “keeping it interesting”; a lab report is not a narrative.
• In a lab report, it is important to get to the point. Be descriptive enough that your audience can understand the experiment, but strive to be concise.
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How to Write the Perfect Chemistry Lab Report: A Definitive Guide

February 11, 2020 By Guest Posts Leave a Comment

Students have to deal with multiple academic tasks, and writing lab reports (lots of them!) is one of them. Its main purpose is to explain what you did in your experiment, what you learned and what the results meant.

Performing experiments and reporting them properly is a cornerstone of on your way into learning chemistry .

But how do you write a chemistry lab report properly?

It’s now time to find out!

Our ultimate guide sheds light on the main parts of lab report writing. You ought to be aware of every section and understand how to complete them properly. Therefore, we have divided our guide into three major sections that are:

• Parts of the lab report;
• A step-by-step review;
• Writing your project.

General Information

It’s necessary to begin with an overview of the main sections that should be present on a laboratory report for chemistry.

Mind that sometimes these sections are called differently but have the same purpose. Some of the sections may be missing, but the general structure should be close to this. Everything depends on the educational institution.

It is important to know that usually lab reports are written after the lab session is finished . This means that you need to have everything previously recorded in your lab notebook . You are supposed to keep track of everything you do in the lab in your laboratory notebook, and then using that notebook to write down your lab report, not the other way around.

Reviewing Every Step

Now, we’d like to go through the main stages of a chemistry lab report. It’s necessary to add brief comments concerning each of them. Your laboratory report begins with a title page. You already know what it consists of. Let’s check how to compose it correctly. The information must be presented on the upper right-hand side of the page. All the points (the title, your name, collaborators, etc.) should be mentioned on the separate line.

Afterward comes the second part, which includes:

• The course title
• Title of the experiment
• Title of the parts within the experiment
• Semester, year, etc. (optional)

This data appears in the middle of the title page.

The next section is the Introduction and it begins with this word in the left upper corner of your report. It should consist of no more than a couple of paragraphs and end with at least one hypothesis.

The body of your project consists of the procedure, materials and methods employed; data; results and observations.  The section Procedure commonly consists of several steps that were followed for the proper conduction of the experiment(s). They could be divided in different parts, and those would describe your actions.

The section Data contains the numerical facts and Observations that provide the changes that took place. Afterwards, you move to the Discussions, in which you ought to plainly explain all the numbers, observations and collected data. Your conclusions provide an overall summary of the entire lab report, and the whole experimental session itself.

Writing a Chemistry Lab Report

The last lap in our “race” is to write a laboratory report . We have already mentioned the main constituents of the title page. Therefore, we can hit the text of your project. Your abstract appears soon after the title page. An abstract is a quick summary that sums up the whole thing (hypothesis to be proven, and conclusions that are reached). Nonetheless, you should leave some space and skip it until the entire project is finished. It is recommended to write the abstract last. The main point is that this section provides a brief review of what your lab report is about and what you’ve managed to achieve.

Main Sections

The introductory part tells your readers what to expect from the project. Write a couple o paragraphs and explain the purpose of your experiment. Including references here is also highly encouraged. The last sentence of your introduction is called a hypothesis or a thesis statement. It shows what you hope to achieve at the end of your research.

The main body consists of several parts and of course, each has its purpose. You should introduce the materials and methods you need to conduct the research. Explain your choice and how your choice helps to conduct a safe and accurate study.

Take instant records of everything that happens during the experiment in your lab notebook . Never rely on your memory!

Afterwards, you’ll interpret the data and explain it using plain words. Don’t draw any conclusions when you record data and don’t explain it in the section called Results. This function should be fulfilled in the sections Discussions or Analysis sections, which should come right afterwards.

Your conclusion makes a brief summary. It should consist of 3-4 sentences, not many more. Restate your hypothesis in other words. Mention whether you’ve achieved your initial goal and explain its value.

Importantly, do realize that if a hypothesis cannot be proven, or an experiment doesn’t give you the results you expected, it doesn’t mean that your experiment and lab session was a failure. It is extremely common in chemistry to find yourself on this kind of situations! You only need to be able to explain why you got the results that you got, and how would you go around to fix them!

Further Sections on Your Report

Don’t forget about the contributors (labmates, supervisiors…) to your research.

You should also obligatorily use some secondary sources to support your theory. Therefore, you have to cite and make references according to the assigned writing format. You can reference other articles all over your manuscript (especially in the introduction and discussion sections), but don’t forget to put them together (or at the bottom of each page), and cite them properly.

The final step is to proofread your lab report. You’re free to use reading aloud and in your head, reading everything again, and using special grammar and spelling checking applications.

To sum up, keep in mind all these guidelines when you’re assigned to write a lab report. Thus, you’ll never miss something important, which can cost you essential grades. Write each section properly to receive the highest grades for your experiment. Always be clear, cite the appropriate references, and be objective with your analysis and conclusions!

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How to Write Hypothesis for Lab Report

• How to Write Hypothesis for…

What Is a Real Hypothesis?

A hypothesis is a tentative statement that proposes a possible explanation for some phenomenon or event. A useful hypothesis is a testable statement that may include a prediction.

When Are Hypotheses Used?

The keyword is testable. That is, you will perform a test of how two variables might be related. This is when you are doing a real experiment. You are testing variables. Usually, a hypothesis is based on some previous observations such as noticing that in November many trees undergo color changes in their leaves and the average daily temperatures are dropping. Are these two events connected? How?

Any laboratory procedure you follow without a hypothesis is really not an experiment. It is just an exercise or demonstration of what is already known.

How Are Hypotheses Written?

• Chocolate may cause pimples.
• Salt in soil may affect plant growth.
• Plant growth may be affected by the color of the light.
• Bacterial growth may be affected by temperature.
• Ultraviolet light may cause skin cancer.
• The temperature may cause leaves to change color.

All of these are examples of hypotheses because they use the tentative word “may.”. However, their form is not particularly useful. Using the word may do not suggest how you would go about proving it. If these statements had not been written carefully, they may not have even been hypotheses at all. For example, if we say “Trees will change color when it gets cold.” we are making a prediction. Or if we write, “Ultraviolet light causes skin cancer.” could be a conclusion. One way to prevent making such easy mistakes is to formalize the form of the hypothesis.

Formalized Hypotheses example: If the incidence of skin cancer is related to exposure levels of ultraviolet light , then people with a high exposure to uv light will have a higher frequency of skin cancer.

If leaf color change is related to temperature , then exposing plants to low temperatures will result in changes in leaf color .

Notice that these statements contain the words, if and then. They are necessary for a formalized hypothesis. But not all if-then statements are hypotheses. For example, “If I play the lottery, then I will get rich.” This is a simple prediction. In a formalized hypothesis, a tentative relationship is stated. For example, if the frequency of winning is related to the frequency of buying lottery tickets . “Then” is followed by a prediction of what will happen if you increase or decrease the frequency of buying lottery tickets. If you always ask yourself that if one thing is related to another, then you should be able to test it.

Formalized hypotheses contain two variables. One is “independent” and the other is “dependent.” The independent variable is the one you, the “scientist” control, and the dependent variable is the one that you observe and/or measure the results. In the statements above the dependent variable is underlined and the independent variable is underlined and italicized .

The ultimate value of a formalized hypothesis is it forces us to think about what results we should look for in an experiment.

For the “ If, Then, Because ” hypothesis…you would use: “ IF pigs and humans share the same nutritional behaviors, THEN their internal organs should look relatively the same BECAUSE of similar function and composure.” That is an example. For the “If, Then, Because” you should follow this guideline:

IF X and Y both do or share this, THEN this should be found/confirmed, BECAUSE of this fact or logical assumption.

Example Question : How does the type of liquid (water, milk, or orange juice) given to a plant affect how tall the plant will grow? Hypothesis : If the plant is given water then the plant will grow the tallest because water helps the plant absorb the nutrients that the plant needs to survive.

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Author:  William Anderson (Schoolworkhelper Editorial Team)

Tutor and Freelance Writer. Science Teacher and Lover of Essays. Article last reviewed: 2022 | St. Rosemary Institution © 2010-2024 | Creative Commons 4.0

16 Comments

How would I write a hypothesis about a flying pig lab?

your lab hypothesis should have been written before the experiment. The purpose of the hypothesis was to create a testable statement in which your experimental data would either support or reject. Having a hypothesis based on a logical assumption (regardless of whether your data supports it) is still correct. If there is a disagreement between your hypothesis and experimental data it should be addressed in the discussion.

So you can go ahead an choose a hypothesis for either increase or decrease of adipogenesis after the inducement of insulin and not be wrong….as long as it is correctly formatted (see examples above).

Hey, I am having trouble writing my hypothesis.. I am supposed to write a hypothesis about how much adipogenesis was produced after the inducement of insulin. However, after proceeding with the experiments the results were On/Off .. meaning it will increase, decrease, increase, etc.. so it wasnt a constant result. It was supposed to be increasing.

please help!!!

this is very helpful but i don’t know how i would structure my hypothesis. i’m supposed to come up with a hypothesis related to the topic ‘how does mass effect the stopping distance of a cart?’. Could you help?

Thank you so much, it really help alot.:)

This is a rather difficult usage of this construct. It would most likely follow

“If the empirical formula of (enter compound’s name) is (enter compound’s formula) then it would be expected that combustion of _________ would yield _________, because (enter your rationale)

Need more background info.

For the “If, then, because” hypothesis I am doing an experiment to determine the empirical formula by using combustion but I am unsure on how to formulate the hypothesis using this structure.

For the “If, Then, Because” hypothesis…you would use: “IF pigs and humans share the same nutritional behaviors, THEN their internal organs should look relatively the same BECAUSE of similar function and composure.” That is an example. For the “If, Then, Because” you should follow this guideline:

Thanks, really helpful. Just one question, what about the ‘because’ part? right after the ‘if’ and ‘then’ parts?

I really need help for onion skin lab hypothesis for class

@Lauren An if/and statement is not usually apart of the convention. What exactly do you need help with?

Is there such thing as a if/and statement? I am in 8th grade science an I need to know for my lab report due tomorrow.HELP!!!!

Would have been better if more examples were given

If the purpose of your lab is “To obtain dissecting skills in an observational lab,” you can’t really formulate a testable hypothesis for that. I’ll assume you are doing some kind of pig or frog dissection. Often teachers give general outlines of skills that students are meant to ascertain from an experiment which aren’t necessarily what the actual experiment is directly testing. Obviously to do the dissection lab you need to obtain dissection skills but testing that would be rather subjective unless the teacher provided you with standards or operationally defined “dissecting skills”. If I were you, I would obviously mention it in the introduction of your lab but I am not sure if your teacher wants you to actually format it as a hypothesis; you can ask your teacher for clarification. If making a hypothesis from each purpose was some arbitrary exercise assigned to you then, it could look like this:

“If a student has successful acquired dissection skills, then they will be able to complete this observational lab with satisfactory competence because they utilized these newly acquired skills.”

For the “If, Then, Because” hypothesis…you pretty much have it. You would modify what you posted: “IF pigs and humans share the same nutritional behaviors, THEN their internal organs should look relatively the same BECAUSE of similar function and composure.” That is an example. For the “If, Then, Because” you should follow this guideline:

Thanks for this, it proved to be helpful. However, I do have a few questions. Obviously different teachers or instructors have their own requirements for their classes. How would you write an appropriate Question to follow each purpose in your lab report? For example: If the purpose was, “To obtain dissecting skills in an observational lab,” what question could you formulate with the purpose? (which is answered in the hypothesis)

And if a teacher requires the hypothesis to be in the format “If, Then, Because” how should this be written? I can actively complete the if and then, but I’m unsure how to incorporate the “because’ statement. For example, “If pigs and humans share the same nutritional behaviors, then their internal organs should function comparably and look relatively the same.” (how do i incorporate because?)

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Example of a well-written lab report.

Return to Laboratory report Instruction main page Example of a poorly written lab report

(single-spaced to conserve paper; yours should be double-spaced to leave room for comments)

Ontogenetic Color Change and Mating Cues in Largus californicus (Hemiptera: Largidae)

Carey Booth Box 123 Biology 102 2 February 1995 Lab instructor: Ned Knight Lab day: Friday

Ontogenetic color change at sexual maturation can be useful in identifying an appropriate mate for some organisms. Largus californicus individuals undergo two ontogenetic color changes. First instars are bright red, second through fifth instars are shiny blue-black, and adults are black with orange markings. Adult male mating behavior suggested that the change in color from fifth instars to adults might enable males to discriminate between nymphs and adults. Males mount adults and persist if they have mounted a female and quickly release if they have mounted another male. Males were never observed to mount nymphs. Female color patterns were altered and male's copulatory attempts were timed to determine if color pattern was used by males in mating decisions. The null hypothesis that dorsal color pattern does not significantly affect male mating behavior could not be rejected, therefore the significance of the color change from nymph to adult must be sought elsewhere.

Introduction

Ontogenetic color change at the time of sexual maturation has been shown to be advantageous to fish (Fricke 1980), reptiles (Werner, 1978), and birds (Lyon and Montgomerie, 1986). In general, dull-colored juveniles avoid predation risk and harassment by breeding males, and sexually mature individuals use bright colors to advertise their readiness to mate (Booth, 1990a). In insects, mating cues are often chemical rather than visual (Jacobson, 1972), but there are some exceptions. In diurnal Lepidoptera, adult color pattern plays an important role in the initial phase of mating behavior (Graham et al., 1980). In holometabolous insects, such as Lepidoptera, maturation is associated with dramatic morphological changes, therefore distinguishing between larvae and adults for mating attempts is not difficult. The recognition of maturity is more difficult in hemimetabolous insects where late instars may be similar to adults in size and shape. The possibility that ontogenetic color change in some Hemiptera may have evolved as an indication of maturation has not been investigated experimentally.

The mating behavior of male Largus californicus suggests that males may be using visual cues, perhaps in addition to pheromonal cues, to distinguish between fifth instars and adults for mating attempts. Fifth instars are shiny blue-black and almost adult-sized. Adults (both males and females) are black with orange borders around the thickened portion of the hemelytra and pronotum (Booth, 1990b). Although males were never observed to mount nymphs, they do mount other adults, and persist if they have mounted a female or release within a few seconds if they have mounted another male. Their distinctive courtship behavior allows an observer to identify immediately the initiation of a mating event. This consists of the male orienting towards the female when he is approximately 1 cm away, rapidly waving his antennae, leaping onto the female's back, and agitatedly grabbing the female with his legs. As their genitals do not immediately join, it is possible to separate a pair before they actually mate.

These bugs do not fly and are easily handled and painted without significantly disrupting their normal behavior. Experiments were designed to determine if males use color cues in their mating decision and if their behavior could explain the significance of the ontogenetic color change from fifth instars to adults. The null hypothesis that dorsal color pattern does not significantly affect male mating behavior was tested.

Materials and Methods

The experiment was performed outdoors at the Main Campus Reserve at the University of California, Santa Barbara on January 31, 1988. Bugs were collected from the Reserve on the morning of the testing day. Tests were performed when the bugs are normally active (1030 to 1430 hours) and control tests were interspersed between experimental tests so that time of day, temperature, cloudiness, and other environmental variables would be approximately the same between experiment and control.

An acrylic black paint and clear finish were used in each treatment. The first treatment was black paint and clear finish on the ventral surface of the female to control for the smell of the paints without altering the black and orange pattern on the dorsum. The second treatment was clear finish on the dorsum to control for covering the dorsal surface, which may reduce any scent emitted or otherwise affect the female's behavior. The third treatment was black paint on the dorsum to mimic the color of the fifth instars. The three treatments will be referred to as normal, clear, and black for brevity.

One female was used for all three treatments to hold other aspects (size, shape, scent) of the female's attractiveness constant. The order of presentation of the three treatments was necessarily the same for all males, as the one female in each experiment could only have black paint added after the normal and clear treatments. This design allows for a repeated measures analysis of variance as each male is tested with the same female under three different paint conditions.

After each painting, the female was placed in a clear plastic 9 x 7 x 3 cm box. Males were held separately in labeled plastic petri dishes. Each male was introduced one at a time into the box at the point farthest from the female. He was removed when he mounted the female or after an arbitrarily chosen time of 270 seconds had elapsed, whichever came first. The time to mount or 270 seconds (no-mount) was recorded. The pair was separated before their genitalia joined so no actual mating occurred. After all 15 males were tested, the female was painted for the next treatment and the males were tested in the same order.

To control for the possibility of males tiring by the second or third trial, a similar number of different males were tested three times each with one untreated female; i.e. no changes were made to the female between trials. Trials were alternated between experimental and control males throughout the day of testing. A total of two females (one experimental and one control) and 29 males (15 experimental and 14 control) were used.

Statistical analyses were performed using the StatView program on a Macintosh microcomputer. One-way, repeated measures ANOVAs were used to test for differences in males' time to mount among the three treatments and among the three control trials.

No significant differences were found in males' time to mount among the three treatments or among the three control trials based on a repeated measures ANOVA (Table 1). Males mounted black painted females as readily as females with the typical black and orange pattern.

There was a slight, but not significant, increase in male's mean time to mount for the black treatment as compared to the normal and clear treatments (Figure 1). The 95% confidence intervals were also larger for the black treatment. The first control trial had a slightly larger, but not significantly different, male's mean time to mount as compared to the second and third trials (Figure 2). The male's mean times to mount were lower for the three control trials than for the three experimental treatments.

Because the maximal time males were allowed to stay in the box without mounting the female was chosen arbitrarily, the one case where a male did not mount the female within the allotted 270 seconds could have biased the results (Table 1). After excluding the mount time for the male that failed to mount, the results did not differ qualitatively from the above: no significant differences were found.

By using one female for all three color treatments, any non-color aspects of the female's attractiveness were held constant. As the null hypothesis (that males' time to mount is not significantly affected by color of the female) was not rejected, males evidently used those other traits in seeking a mate. The male behavior of mounting other adults (male or female) and not nymphs may indicate that there are pheromonal differences between nymphs and adults but not between adult males and females. Males release other males rapidly once contact has been made, so chemical cues transferred by touch or other close range signals (such as sound) may be used to distinguish males from females. There are slight shape differences between nymphs and adults (nymphs are more spherical) that could possibly be used by males in mating decisions. Other experiments are necessary to determine the nature of the communication between adults and between adults and nymphs.

Among hemipterans, several species use pheromones as mating cues. Males of the southern green stink bug (Nezara viridula) release a pheromone that attracts females, males, late-stage nymphs, and a parasitoid (Aldrich et al., 1987). Females of Dysdercus cingulatus and Pyrrhocoris apterus also produce substances attractive to males (Osmani and Naidu, 1967; Zdarek, 1970). As these last two species are in the same superfamily (Pyrrhocoroidea) as L. californicus, it is possible that L. californicus females also produce a pheromone that is attractive to males. However, several species in the family Largidae, including L. cinctus (a close relative of L. californicus), have minimal development of the metathoracic scent gland evaporative area (Schaefer, 1972), so their use of pheromonal communication may be limited. The use of pheromones does not rule out the possibility that visual cues may also be important.

Aldrich, J. R., J. E. Oliver, W. R. Lusby, J. P. Kochansky and J. A. Lockwood. 1987. Pheromone strains of the cosmopolitan pest, Nezara viridula (Heteroptera: Pentatomidae). J. Exp. Zool. 244: 171-175.

Booth, C. L. 1990a. Evolutionary significance of ontogenetic colour change in animals. Biol. J. Linn. Soc. 40: 125-163.

Booth, C. L. 1990b. Biology of Largus californicus (Hemiptera: Largidae). Southwestern Naturalist 35: 15-22.

Fricke, H. W. 1980. Juvenile-adult colour patterns and coexistence in the territorial coral reef fish Pomacanthus imperator. Mar. Ecol. 1: 133-141.

Graham, S. M., W. B. Watt and L. F. Gall. 1980. Metabolic resource allocation vs. mating attractiveness: Adaptive pressures on the "alba" polymorphism of Colias butterflies. Proc. Natl. Acad. Sci. 77: 3615-3619.

Jacobson, M. 1972. Insect sex pheromones. Academic Press, New York.

Lyon, B. E. and R. D. Montgomerie. 1986. Delayed plumage maturation in passerine birds: reliable signaling by subordinate males? Evolution 40: 605-615.

Osmani, Z. and M. B. Naidu. 1967. Evidence of sex attractant in female Dysdercus cingulatus Fabr. Indian J. Exp. Biol. 5: 51.

Schaefer, C. W. 1972. Degree of metathoracic scent-gland development in the trichophorous Heteroptera (Hemiptera). Ann. Entomol. Soc. Am. 65: 810-821.

Werner, D. I. 1978. On the biology of Tropidurus delanonis, Baur (Iguanidae). Z. Tierpsychol. 47: 337-395.

Zdarek, J. 1970. Mating behaviour in the bug, Pyrrhocoris apterus L. (Heteroptera): ontogeny and its environmental control. Behaviour 37: 253-268.

Table 1. Repeated measures ANOVA on males' time to mount female (in seconds).

a Males' copulatory attempts were timed from point of entry into female container.

b SEM = standard error of the mean

c F = F statistic

d df = degrees of freedom for numerator, denominator

e P = probability value

f Each Largus californicus male was tested with the same female under three different paint conditions. Black and clear paint on the dorsum = Normal treatment. Clear paint on the dorsum = Clear treatment. Black paint on the dorsum = Black treatment to mimic the color of the fifth instar larva.

g Different males were tested three times each with one untreated female = Control trials 1-3.

Figure 1: Mean male mount time (sec) with 95% confidence intervals under three experimental conditions. Each Largus californicus male was tested for time to mount (attempting copulation) with the same female under three different paint conditions. Normal = Black and clear paint on the dorsum to control for odor of paints. Clear = Clear paint on the dorsum to control for covering the dorsal surface. Black = Black paint on the dorsum to mimic the color of the fifth instar larva.

Figure 2: Mean male mount time (sec) with 95% confidence intervals for three control trials. Different Largus californicus males were tested for time to mount (attempting copulation) three times each with one untreated female to control for order of presentation in the experimental treatments.