Why — and How — to Write Lab Reports

­Why write lab reports?

Milena Shahu, Chemistry

Chemistry is an experimental science. The theoretical concepts and principles are usually introduced in the lecture part of the course. The laboratory is important as well because it helps students discover/prove what they learned in the lecture and consolidate their understanding through experimentation. While conducting an experiment in the laboratory, students are expected to understand the scientific process behind the principle they are testing, create a hypothesis, design and complete an experimental study, obtain useful data, and analyze/interpret the data to reach conclusions. It is important for students to communicate their findings with the scientific community (in this case, the professor of the course, teaching assistants and their classmates). This enhances students’ learning and helps faculty evaluate how well students are learning. The best way to convey their findings (or prove if they are legitimate) to the scientific community is by writing a clear and concise scientific lab report. The practice of writing a scientific report is useful and pedagogical if taught as part of the learning process, because it strengthens skills important for chemists, including logical organization, attention to detail, writing, communication, and critical thinking.

The lab report has a similar format to a chemistry journal article. In general, journal articles mirror the scientific method and comprise four major sections: Introduction, Experimental Methods, Results, and Discussion. Journal articles also include a title, abstract, conclusions, references, and acknowledgements. The lab report handout guides students through the process of properly writing of each of the above sections. As a result, students’ scientific writing skills improve throughout a laboratory course. Other faculty in the Chemistry Department use similar handouts to guide students in this writing process.

Since the lab courses count for the Integrated Writing requirement at Georgetown, the goal is to ensure that our chemistry/biochemistry majors master college level writing skills. Students improve gradually over four undergraduate years, as they move to the more advanced level lab courses, where they are required to write a more detailed report, which includes statistical data analysis and error analysis. By the time our majors graduate, they are well prepared and possess the necessary skills to write a chemistry journal article.

Here are the guidelines we give to our students.


Besides the experimental work, an important part of the laboratory is the written report, which should clearly show what was done and what results were obtained.  It should be original, which means that you should not copy the lab manual or other materials.  Your lab reports are to be in the format of a manuscript to be submitted to a Journal of American Chemical Society (JACS).

Title page contains the title of the report, the names of the authors, the section, group number, and the date of submission.

Abstract consists of a few paragraphs, usually no longer than a half page.  In this part, you should summarize the results of the experimental work and give the main conclusions.  Be quantitative. The abstract is generally written after you have evaluated your results.

The Introduction section should give an introduction of the theory, and explain why you are doing this experiment and what is the purpose/problem that the experiment is focused on. What significance does the problem that you are trying to solve have?  If you need to present some equations, they should be presented here in separate lines and also be numbered. The symbols used in the equations must be explained clearly when they appear for the first time.

In the Experimental section you should describe the experimental procedure. You should not repeat the information given in the lab manual, but make a reference to it.  You should give details of the procedure only if it is not given in your lab manual or if you modified it.  A figure of the apparatus should be illustrated only if you assembled it or you were using a special apparatus, compared to the one given in the lab manual.

The Results section should include tables, graphs, and sample calculations.  All the results should be presented even if there is any inconsistency with the theory or with what is expected.  You should explain why this happens in the “Discussion” section.  If you are using any computer program, you should make a reference to it.  All the tables should have titles and should be numbered.  The column headings should be labeled with the units specified.  Graphs should be presented as figures. All the graphs should have numbers and a short legend. Graphs should have labeled axes and clearly show the scales and units of the axes.

In the Discussion section you should present your final results.  What do they mean?  Your results can be compared with the theory or experimental values from literature.  If there is any inconsistency, you should try to explain it.  You should give a discussion of probable experimental errors, such as random and systematic errors.  You should calculate the experimental errors if you are provided with literature or actual values of the parameters that you are determining.  Other topics you can discuss are: comparison of the experimental method used with other methods, suggestion for a better experimental method, discussion of any difficulties that you might have faced or any approximation you used, etc.

Conclusions section is a brief summary of your results.  You can talk about your interesting findings.

References must be listed at the end of the report and should have at least two primary sources. You should cite all the sources used.