Biology – Writing Lab Reports

Writing in Biology: the Lab Report

The most common piece of writing you will do in Biology is the lab report.

Lab Report Structure

General 

• Instructions for lab reports will vary slightly according to your professor and TA; make sure to follow the guidelines specific to your lab. 
• Consult your lab manual while writing your report. 
• The information is objective and written in a way that is short and concise. 
• The entire experiment should be repeatable from the information given and unless there were errors, the results should be the same.  
• All of the conclusions should be supported with data from the results.  
• Lab reports are traditionally written in the third person and in past tense; however, many biology courses today require that you use the first person. Always check with your professor or TA for their preference.  

Title 

• A title is important to any lab report and Should be a succinct, specific description that summarizes the purpose of the lab. 
• It is never a good idea to use the title from the lab manual.
• An example title might be “Finding an Unknown Dilution by Measuring Optical Density of Serial Dilutions.”

Abstract

• Although the abstract is usually first in the lab report, it is easiest to write this section last after you’ve written the rest of the report.  
• An abstract summarizes the content of the entire lab report in a single paragraph and should be able to stand alone.  
• It should be informative enough so that a reader can decide if it would be in their best interest to read the report after reading the abstract. 
• Generally no more than 250 words, it consists of a sentence or two from each section of the report.  

• An abstract should summarize five key points, which are representative of the parts of a lab report: 
  • Why the experiment was conducted (introduction)
  • The problem being addressed (introduction)
  • What methods were used to solve the problem (materials/
  • methods) 
  • The major results obtained (results) 
  • The overall conclusion from the experiment as a whole (discussion)

• Why the experiment was conducted (introduction) 
• The problem being addressed (introduction)
• What methods were used to solve the problem (materials/methods) 
• The major results obtained (results) 
• The overall conclusion from the experiment as a whole (discussion)

• Although it should be concise, it is important to include enough transitions to create a logical thread that the reader can easily follow.
• Abstract are typically written in the passive voice. For example, “the ball was hit by the boy” (passive) versus “the boy hit the ball” (active). 
• Results can include numerical data if desired (although must be limited) in order to support statements of the overarching conclusions. 

Introduction 

• It is best to save this section for the end because the introduction gives an outline for the entire lab report in addition to giving background information about the topic.  
• The introduction includes the purpose of doing the experiment, background information needed to understand the experiment or procedures, and at least one hypothesis that makes an educated guess from the background information. 

• An introduction should:
  • Outline the purpose of the experiment 
  • Ask the question: why is the study important? 
  • Use background information to validate and expand on the importance

• Depending on the course level, the introduction can be rather lengthy. There is often an extensive amount of background research involved; one of the main purposes of the introduction is to really show your TA/professor that you understand the implications and consequences of the experiment, and you’re expected to do this through your background research. 
• While writing the introduction keep in mind that you should state the problem or question and then include factual details that are supported by references.
• Any important definitions that are needed to understand the experiment should be found in the introduction. 
• Though you should avoid directly taking information from the lab manual, you can highlight relevant or important information from the lab manual text that you could use in your introduction or conclusion sections. You can then look in online journal databases for relevant journal articles that describe that information. Often citations for possible sources are listed in the lab manual itself, so it is best to look here first. 

Method and Materials 

• This is a good section to begin  
• The method of how data was analyzed should also be explained.  
• Detailed step–by-step account of the procedure a general rule of thumb is to include enough detail so that a fellow biologist could exactly replicate the experiment. There should be no extraneous or subjective detail. Subheadings should be used for easy reference and that you should state the reason for doing something if it is not obvious.  
• Lab manuals are the best reference sources for writing the methods section in a lab report. When writing the methods section, you can follow along the lab manual’s instructions, but try to paraphrase or combine several steps into one sentence and sift through whether information in the lab manual is relevant for an actual lab report (hint, not all of it is!).

Results 

• By writing the Materials and Methods section first, it is easier to order the Results section based on when data was collected.  
• The goal is to summarize the data. Any verbalization of the results should be a summary that draws attention to key points in figures. Therefore, it is best to create the figures first and then go back and verbalize the results. 
• The results include all data found, observations made, figures, tables, charts, and graphs. All charts, graphs, figures, and tables are kept separate and referred to in the results when they are being explained.
• Systematic presentation of data; includes all relevant findings that contribute to the final conclusion 
• Each set of data is numbered (Figure 1, etc.), labeled, and followed by a short explanatory paragraph 
• This is not a discussion of the experiment; it is an objective layout of your data. There should be no analysis of the results (as this will be in the Discussion section).

Discussion 

• The Discussion section is an examination of the results in relation to expectations about how the experiment would turn out, this section is written after the Results section.  
• This is the most significant section of the lab report. The results are analyzed and related to the hypothesis and purpose. They are compared to what was expected and any differences should be explained.  
• The writer should go in deeper and explain the “so what?” of the experiment 
• All weaknesses or errors in the experiment, including human error, are mentioned and it is explained how they had an impact on the results. Even if the experiment failed, the lab report can be saved by explaining the errors, showing what they did to the results, and explaining what should be done differently next time to prevent this failure.  
• Further questions on the subject or improvements in the lab should be mentioned in this section. 
• The expectations should be stated with supporting references and then the results of the experiment should be analyzed in relation to the expectations. Reasons for unexpected results should also be offered. 
• Interpretation of results: What did the experiment demonstrate?
• Compare and contrast expected findings with actual findings 
• Explanation of unexpected results
• Remember, your results never “prove” anything; they only ever support the hypothesis. Be careful with scientific vocabulary. The discussion section, like the introduction, is another crucial place to demonstrate your grasp of the material; it’s important to be thorough, but equally important to be concise. 
• The discussion section is where you typically expand upon your results, interpreting them and relating them back to your hypothesis, and then describing how they connect to the greater scientific field. The post lab questions, if available in the lab manual, will help guide your analysis of your results towards specific topics or overarching ideas that your instructor is expecting you to explore at the end of your lab report. Often they are required! These questions can also give you a good sense of how to relate your results to the broader scientific community. 

References/Works Cited 

• Any sources used in the lab report should be cited in the report and then documented in the references. These sources might include the lab manual, textbook, or some other source used to write the background information in the introduction.  
• Any information that is not common knowledge should be cited. 
• Generally, students use APA format for citations and references, but check with your instructor. 
• After all the other sections have been written, a Reference section can be included based on what sources were used throughout the lab and a Title should be included. 
• Whether or not you even have a works cited/references section depends, once again, on the level of the biology course. In upper level courses you are often required to have several outside sources, which provide the background information found in the introduction. These sources are usually from scientific journals.