How to Write a Lab Report


The purpose of this (non-existent) lab is to demonstrate how to write a lab report. A lab report is defined as a document 2 to 6 pages in length that clearly and concisely describes the procedure and results of the lab exercise, followed by a discussion and a conclusion. Throughout, the writing must show an understanding of the topic, and support all generalizations with details. In addition, proper use of English will make the lab report more readable, as will the use of a serif font like Times New Roman, and the existence of reasonably sized margins. Avoid wordiness, repetition, and colloquialisms. Lastly, this document must be handed in on time with all pages stapled together


Part A

  1. Read the lab instructions before coming to lab. This may seem tedious, since they will necessarily be read again during the lab. However, knowing what is at the end of the lab often allows you to focus your efforts during the lab. This means that you may be able to finish your work and leave early.
  2. Come on time to the lab. It is often worth your while to listen to what your professors and TAs tell you at the beginning of the lab, rather than work while they speak. These talks at the beginning of lab include corrections to the lab assignment, explanations of technical problems you may encounter, explanations of the theory behind the lab, or an announcement that you are to skip a section.

Part B

  1. Do the lab. While you are working, you may want to take a few notes about possible answers to the discussion questions. Print all of your graphs with titles. Remember to save your work, since computers sometimes crash.
  2. Write the lab report. It may be easier to write it in the order that you did it; that is, write both the results and the discussion sections for each topic at a time. Remember, however, that results and discussion must be presented separately. If you are having trouble, go to your TAs office hours. This is preferable to a frantic email the night before the lab is due. If you know that you will be turning in a lab late due to extenuating circumstances, please speak to your TAs about this in advance.
  3. Proofread your lab. This will make your TAs happy, and they are the ones who do the grading. Also, remember to attach all of the graphs that you reference.

Observations & Results

Part A

Having read the lab in advance, it is clear that some of the questions will have simple, factual answers such as 3, yes, or in the desert region of Africa. However, these answers must be presented in full sentences so that their meaning is understood. In addition, a unit must always follow a number. Some data are better presented in tables, such as table 1.


Variable Something (cm) Something else (s) Yet another thing (m2)
A 0 1 1
B 2 3 5
C 8 13 21

As you can see from table 1, these data would be tedious to read in sentences. Also note that the formatting of the table makes it easy to read and understand, and the units are listed in parenthesis

Part B

In some labs, it is easier to number each part of the results section as you numbered the procedure; in others, such as this one, it is unnecessary. Use your best judgment, but be consistent. Graphs, such as graph 1 (page 3), are often part of the results section. In graph 1, it is clear that there is no actual data being examined here. If there were, this sentence would remark on its salient features. Instead, note that the graph is clearly labeled with a title and units. In addition, a trendline is displayed with its equation and r-squared value. There is no legend, because there is only one independent variable.


For this lab, parts A and B are not separated in the discussion. If, however, this were a particularly long or complicated lab covering distinct topics, they might be separated. This section deals with a slightly bigger picture than does the results section, but it is not an overarching summary (thats the conclusion). Here, you must address any major questions asked in the lab, and make connections between your simple answers of your results section and the theory that you have learned. In some cases, it can be difficult to tell whether a question is meant for results or discussion, but it is more important that you answer it then that you put it in the correct place. Sometimes, you will need to reference a source outside of the lab instructions. In that case, you must cite your source; otherwise, it is technically plagiarism.

The discussion section is the most important part of any lab. This is where you can demonstrate your understanding of the concepts of the lab and the course. Your discussion will be greatly improved by providing specific examples for your statements, and comparing expected results to actual data. It is perfectly acceptable to say that you expected something other than what you saw. Try to explain whatever phenomena were seen based on what you have learned in class. Even if your explanation is ultimately wrong, a logical and convincing explanation shows that you understand the material.


Writing a lab can be difficult, but it can also help you solidify what you understand and pinpoint areas in which you need help. A lab that is neat, well written and turned in on time will do better than the same lab done in a slipshod manner. Your TAs are people too, and would rather spend the time helping you understand the material then spend it taking points off of a lab. Good luck!

Updated August 27, 2004
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