To write a lab report, you explain what you tested, how you tested it, what you found and what the results mean. It follows a fixed scientific structure so readers can find and check each part quickly.
This page covers each section in order, how to present data in tables and figures, the writing style scientists expect, an example results paragraph and the mistakes that cost marks most often.
The Sections of a Standard Lab Report
Most lab reports follow the IMRaD pattern: Introduction, Methods, Results and Discussion, with a title and abstract at the start and a conclusion and references at the end. Some courses add an aim, hypothesis or appendices.
Results report what happened; the discussion explains why. Keeping those two apart is the single most important rule.
Lab Report Structure at a Glance
| Section | Question it answers | Tense |
|---|---|---|
| Title | What was studied? | None |
| Abstract | What was done, found and concluded, in brief? | Past |
| Introduction | Why does it matter and what was expected? | Present for theory, past for aims |
| Methods | How exactly was it done? | Past |
| Results | What was found? | Past |
| Discussion | What do the results mean? | Past for results, present for interpretation |
| Conclusion | What is the main takeaway? | Present |
| References | Which sources support the work? | None |
Writing Order, Step by Step
You do not have to write the sections in the order they appear. Many students find this sequence faster and more accurate.
- Process your data and draw the tables and figures.
- Write the methods while the procedure is fresh.
- Write the results around your tables and figures.
- Write the discussion, interpreting each key result.
- Write the introduction, so it sets up the discussion you actually wrote.
- Write the conclusion, abstract and title last.
- Add references and proofread numbers and units.
Title, Abstract and Introduction
A good title names the variables and the system: "Effect of temperature on the activity of catalase from potato tissue" tells the reader exactly what to expect.
The abstract summarizes the aim, method, key result and conclusion in one paragraph, often 150 to 250 words. Write it last.
The introduction gives the background theory, explains why the experiment matters and states the aim and hypothesis. Move from general context to the specific question you tested.
Methods
The methods section should let another scientist repeat your experiment. Describe materials, equipment, procedures, quantities, conditions and how data was recorded and analyzed.
Write in continuous prose in the past tense, not as a numbered list copied from the lab manual, unless your course asks for that. The passive voice is common ("the solution was heated to 40 °C"), though many journals now accept the active voice too.
Results, Tables and Figures
Present your findings without interpretation. Use tables for precise values and figures for trends, and refer to each one in the text.
- Number tables and figures in order and give each a clear title.
- Label axes with the quantity and the unit.
- Report means with a measure of spread, such as standard deviation.
- Give the result of any statistical test with its value and significance.
- Do not repeat every table value in the text; highlight the key pattern.
Example results paragraph. Catalase activity increased with temperature from 10 °C to a peak at 40 °C, where the mean rate of oxygen production was highest (Figure 1). Above 40 °C, activity fell sharply, and almost no oxygen was produced at 70 °C. Variation between the three repeats was smallest at the lower temperatures (Table 1).
Notice that the paragraph describes the pattern but does not yet explain it. The explanation, enzyme denaturation, belongs in the discussion.
Discussion and Conclusion
The discussion interprets the results. Did they support the hypothesis? How do they compare with theory and published findings? What explains any unexpected results?
- Start with the main finding and whether it supports the hypothesis.
- Explain it using scientific theory.
- Compare with expected values or other studies.
- Discuss sources of error, distinguishing random from systematic error.
- Suggest specific improvements or further experiments.
The conclusion is short: restate the main finding and its significance in two or three sentences, without new information.
Scientific Writing Style
Lab reports value precision over flourish. Every sentence should be clear, specific and supported.
- Use exact numbers and SI units.
- Avoid vague words such as "a lot" or "quite"; give the value.
- Say "the results suggest" or "support", not "prove".
- Define abbreviations on first use.
- Keep the same tense within each section.
Common Lab Report Mistakes
| Mistake | Fix |
|---|---|
| Interpreting data in the results | Move explanation to the discussion |
| Copying the method from the manual | Rewrite in past-tense prose, noting any changes you made |
| Unlabelled axes or missing units | Label every axis with quantity and unit |
| "Human error" as the only limitation | Name specific sources of error and their likely effect |
| Claiming the results prove the hypothesis | Say the results support or do not support it |
Final Checklist
- The title names the variables and system.
- The abstract covers aim, method, result and conclusion.
- The introduction ends with a clear aim and hypothesis.
- The methods could be repeated by another student.
- Results are presented without interpretation, with labeled tables and figures.
- The discussion explains results with theory and evaluates error.
- References follow your required style.
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Frequently Asked Questions
Results report what you found, without interpretation. The discussion explains what the results mean and why they occurred.
The passive voice is traditional, especially in methods, but many courses now accept the active voice. Follow your instructor's preference.
It depends on the experiment and level. Many undergraduate reports are 1,000 to 3,000 words. Check your rubric.
Most formal lab reports include one. Some short practical write-ups do not. Follow your course guidance.
Report them honestly and explain possible reasons in the discussion. Unexpected results can make a strong discussion.
Usually in an appendix, with processed data in tables or figures in the results section.
Yes. Send your data and lab manual, and the writer builds the report on your actual results.