Successful Lab Reports


A lab report is neither a term paper nor a scientific paper. Your report needs only a small amount of background information to give context to your own experiments or observations. On the other hand, while a lab report must have the structure of a scientific paper, it has a different audience and purpose. Your lab report is written to your Teaching Assistant, who already knows all about the work, to show that you understand the process and significance of the experiment. In contrast, a scientific paper is written to fellow scientist to present and discuss new information and ideas.



1) Introduction

Why did you study this problem?


  The Introduction gives the background to the work, starting with the broad context of the study and leading up to the hypothesis-the question studied, or the pattern sought.

  You need to be able to choose relevant facts from the scientific literature, paraphrase them, and reassemble them into your own logical sequence, citing the sources to support each statement. Don't use your lab manual as sole source!

  Introduce the methods and then the hypothesis. Outline scientific purpose(s) and/or objective(s). Never write that the objective was to 'learn the technique' or 'to measure this or that.'


2) Materials and Methods

What did you do? How did you do it?

In this section you will describe how and when you did your work, including experimental design, experimental apparatus, methods of gathering and analyzing data, and types of control.

  Using your lab manual, handouts, and notes taken during the lab as a guide, describe in paragraph form the experimental procedure you followed. Be sure to include enough detail about the materials and methods you used so that someone else could repeat your procedure. A Generally, this section attempts to answer the following questions:

What materials were used?
How were they used?
Where and when was the work done? (This question is most important in field studies.)



3) Results

                                                        What did you find?

In the results, you present your observations and data with no interpretations or conclusions about what they mean. A well-written and well-organized results section will provide the framework for the discussion section.

 - Record all your results, using complete sentences, usually in the order the observations were made.

 - Tables and graphs should be used to supplement the text and to present the data in a more understandable form.

 - The written text of the results section may be as short as one sentence summarizing the highlights and directing the reader to specific tables and figures.

 - Include results that went "wrong" or were unexpected. This may be useful information for someone trying to repeat the experiment.

 - Use both words and numbers to describe your results, and use proper terminology.

 - Use past tense to describe your results.

 - Sample or detailed calculations for a lab report  

  ### Tables and Figures

Tables and figures are often used in a report to present complicated data. Use the following guidelines to incorporate them effectively.

  • Tables are referred to as tables, and all other items (graphs, photographs, drawings, diagrams, maps, etc.) are referred to as figures.

  • Numbering: All tables and figures must be numbered. Tables and figures are assigned numbers in the order they are mentioned in the text. Tables and figures are numbered independently of each other (i.e., Table 1 and 2, and then Figure 1 and 2 as well).

  • All tables and figures must have self-explanatory titles so that the reader can understand their content without the text.

  • Labeling: Tables are usually labeled at the top and figures at the bottom.

  • Each table or figure MUST be introduced within the text, with a comment that should point out the highlight(s) or significant trend(s), not every piece of data that is shown. e.g.,

  • Tables and figures may be placed at the end of the paper, or within the text as soon as possible after they are mentioned without interrupting the text (i.e., at the end of a paragraph or section). Check with your professors for their preference.

  • Avoid referring to the table below because you don't know exactly what the final placement of the table will be. Refer to the specific table or figure number, and the readers will always be able to find the information.

  • The tables and figures should enhance the report, but the reader should be able to understand and follow the results even if the tables/figures were removed.


5) Discussion

What does it mean? How does it relate to previous work in the field?


Explain what you think your data mean.
  • Describe patterns and relationships that emerged.

  • Discuss why you observed what you did, how it happened (or the most likely reason), and how it relates to the purpose of the experiment.

  • Compare these results to trends described in the literature and to theoretical behavior.

  • Support your interpretations with references to course material, the lab manual, and comments from the TA or instructor during the lab. You may also be asked to use other resources (peer reviewed journal articles) for a more in-depth discussion; if you do, remember to reference properly (see References in this handout).

  • Continue to be descriptive; the readers may not read each result and jump to the discussion to find out why it happened, so provide them with enough information to understand the discussion. Remind the reader of your own results, when relevant, without repeating endless details from Results.

  • If your result section was well organized, you can follow it as a guide while you are writing the discussion. You can refer to the same tables and figures to explain the changes/trends/unexpected results.

  • Accept or reject your hypothesis and explain why. It is acceptable to reject your hypothesis as long as you can prove it to be untrue and explain why the results did not turn out as you predicated. You can't argue the results, but if something went wrong or was damaged, disturbed, or contaminated; if there were changes to the experimental procedure; or if equipment was faulty, you need to include this information and explain how it may have affected the results.

  • If your lab manual includes questions to be answered in the Discussion, integrate your responses into a logical discussion, rather than answering them one by one. And don't include only the answers to the questions - use them as a guideline for supplementing your discussion, not limiting it.

  • Your final paragraph is the conclusion. Include a brief restatement of the purpose and the main results and how they are relevant to the field of study. Also include any future direction for your results or changes you would make the next time to produce results that are more significant or noteworthy.

  • This section will be written in the past tense when you are describing your experiment, and present tense when comparing to current theory.



The Discussion answers the question. What do the results mean? It is essentially an argument about hypothesis based on the results. Since all the experiments or observations (presumably!) relate to the hypothesis in question, you must in the end draw your conclusion as to whether the hypothesis is supported. Although you could discuss results 1, 2, 3 in order, you will find that many comments either refer to several results or compare two or more results. You can more usefully organize the Discussion into a number of smaller questions:


1. What is your interpretation of the results, in light of the hypothesis and the published literature?

2. What are the significant sources of error in the results?

3. Therefore, how reliable are the results?

4. Do the results support the theory (or hypothesis)?

5. What changes in procedure would give better results; what additional experiments would help support or refute the theory (or hypothesis)?


Remember that whether your experiment worked as planned or deteriorated into complete chaos, you can write a good report.

The key section in the report is the Discussion, because it is where you show that you understand what should have happened and what did happen.


You should start the Discussion by stating your interpretation of the facts, in as positive a way as you can (without exaggeraing !), perhaps comparing or contrasting them to the literature. Only then should you tackle reliability and errors. Never start the Discussion by lamenting what wet wrong; consider the strengths of your data first.


 You should freely admit a failure to get results; show that you understand what might have gone wrong. Notice that there is an important difference between negative results and a failure to get results.


  The point of examining the error is to evaluate the results. Do not assign blame or assume any guilt.. even if you or your lab partner did something really stupid! Give a cool scientific explanation.


 Finish the Discussion by drawing your conclusions and relating them to the Introduction. Don't make grandiose claims for a modest experiment. You don't have to pretend that your experiment or observations advanced science, and it looks silly if you do. And don't conclude that what happened was that you learned how (how not!) to do the experiment. Address the hypothesis. If appropriate, suggest how to improve the experiment, or what additional experiments would be helpful.


  Leave the reader with a positive message. This is the end of the text of your report, and you want you TA to feel that the report is complete and satisfying. The worst possible way to end is just to stop at the end of a litany of errors.  One good way to end is to return to an idea in the Introduction, especially one relating to the hypothesis.


 ### Assessing the results : Notes for the Discussion


Sources of error

Your data will have various errors which need to evaluate. The obejective is to discover the reliability of your data, the extent to which they can be trusted to tell you about scientific reality. You are analyzing after the fact.


Accounting for the sources of errors has nothing to do with assigning blame.


Do not blame yourself or other for what went wrong. Simply consider the sources of error and the extent to which they affect the data.


Here are some potential sources of error.


Experimental Errors

Sampling errors

Errors in measurement

Errors in recording or recopying

Errors in computation

Differences from published procedures


List the changes and sources of error and try to decide for each if it would have a major or a minor effect on the results- or no significant effect - and in which direction the results would change, if at all. You need to know something about the process studied to make such judgments.



6. References & Literature cited


Also called "Literature Cited" or "References Cited," this is a list only of papers and resources actually mentioned (cited) within the report. (NOTE: A "Bibliography," on the other hand, refers to a list of all materials used to get background knowledge on a subject; you will not usually be required to include one in a scientific lab report.)


Scientific lab reports are written for the sole purpose of sharing information. If readers want more information about something, they need to be able to find the exact place it was originally written. References also give credit to the person who did the work and provide your work with authority.


- The reference list is provided on a separate page at the end of the report.

- Remember that ALL information within the report that is not your original work or ideas should be referenced (even if not quoted directly, but paraphrased or summarized - quotations are rare in scientific writing).

- Reference your lab manual, textbook, and any journal articles used.



1. SUCCESSFUL LAB REPORTS A Manual for Science Students, Christopher S. Lobban & Maria Schefter