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Concluding a Great Experiment with an Excellent Lab Report

written by: Stephanie Torreno•edited by: Wendy Finn•updated: 12/7/2011

You have performed an experiment for a science course, obtained results, and can use those results to draw conclusions about a scientific process or principle. Now, you have to write all this information clearly and persuasively, but how do you do it?

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    Writing a Lab Report that Earns Good Results

    A major part of conducting a scientific experiment comes after the lab work – that is, writing a lab report. After all, you need to show your instructor the information you gathered and the findings that resulted from your project. Before you think of this work as just another assignment, though, consider your role not just as a student, but as a scientist. As a member of the scientific community, your role is to inform other scientists about your work. In reading your report, fellow scientists primarily want to know two things. First, they want to know the information you gathered. Second, they need to know if the results are legitimate.

    A lab report is written with these two goals in mind, especially if your findings contribute to or disagree with previous ideas. While you should follow your instructor’s specific guidelines, a scientific lab report generally has four main sections: Introduction or Purpose, Materials and Methods, Results, and Discussion. This format may appear in slightly different variations, such as including an abstract, stating the hypothesis in a separate section, or calling the “Discussion" section “Conclusions." Below is a detailed explanation of how to write a good lab report.

    Introduction / Purpose

    The Introduction can contain four elements: the purpose of the experiment, background research, your hypothesis, and justification of your hypothesis. The purpose differs from your hypothesis because it is more general and tells what you hope to gain from the experiment. Then, you may want to begin narrowing your topic by introducing some background information, or how your work connects to past research. This previous research can make it easier to transition to your hypothesis, which should be stated in one sentence as precisely as possible. Working on your hypothesis should actually be done before you begin your experiment. Your hypothesis should include the dependent variable and the independent variable. Finally, go beyond simply stating your hypothesis by justifying it with your own logic or observations. In other words, why did you think your hypothesis could be supported with evidence?

    Materials and Methods

    In this section, you will list everything needed to complete the experiment and the procedure you followed during it. Your writing should be very detailed and describe exactly how you tested your hypothesis and why you did it this way. Write the details of your procedure so that the reader could duplicate your experiment. Do not write this as a recipe, however, and tell the reader how to perform the experiment. Tell what did happen, using the past tense, since you did the experiment before writing this report.

    Remember not to reveal the results of the experiment – yet. In the Methods section, you can tell that you recorded the results, and how you did it (for example, in a table). Results, though, will appear in the next section.

    Results

    This section is often the shortest, but most important, part of your report. It is the shortest because it describes the data obtained from the experiment. Depending on the complexity of your experiment, you will use tables, charts, and graphs to illustrate your data. Your text should refer to these illustrations, but tables, charts, and graphs should not repeat what is written in the text or present irrelevant information.

    The most important section, the Results section tells whether your hypothesis was supported or not supported by the data. Resist drawing conclusions and just inform the reader of the facts. Do not present any arguments or interpretations.

    Discussion or Analysis

    This section calls for interpreting the data and drawing conclusions about the experiment. You should begin by stating whether your hypothesis was supported or not. Then, you should explain why you think this outcome occurred. You may want to acknowledge any limitations or weaknesses in your experiment. To end your report strongly, you may want to relate your findings to previous research or to ongoing discussions in the scientific community. Ending your report by discussing the theoretical or practical implications of your findings conveys the meaning of the bigger picture, too.

    The final steps in writing a good lab report involve listing your references and checking the mechanics of your writing. Remember, each source you list should have a corresponding citation in the body of your report. Finish your report by proofreading for spelling and grammatical errors. An error-free report will leave a lasting and positive impression on the scientific community - and your instructor.

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    References

    The University of North Carolina at Chapel Hill: Handouts and links. (2007). Scientific reports. Retrieved July 7, 2010, from www.unc.edu/depts/wcweb/handouts/lab_report_complete.html