To write a lab report, you explain what you tested, how you tested it, what you found and what the findings mean, in a fixed order of sections. Each section has one job, and marks are lost when they blur together.
This guide walks through each section, the conventions for tense and voice, and the common mistakes that cost marks, with an example of results and discussion written well.
The Lab Report Sections at a Glance
| Section | Its job |
|---|---|
| Title | Say what was investigated, ideally naming the variables |
| Abstract | Summarize aim, method, key results and conclusion |
| Introduction | Give background theory, the aim and the hypothesis |
| Methods | Describe what was done so it could be repeated |
| Results | Present the data, without interpretation |
| Discussion | Interpret the results, compare with theory and assess error |
| Conclusion | Answer the aim and state whether the hypothesis was supported |
| References and appendices | List sources and include raw data if required |
What Goes in Each Section
Title
Make it informative. "The effect of temperature on catalase activity in potato tissue" tells the reader far more than "Enzyme experiment".
Abstract
Write it last. In a short paragraph, give the aim, method, main numerical results and conclusion. Check your lab manual for the word limit.
Introduction
Explain the scientific principle being tested, cite relevant theory or earlier studies, and end with a clear aim and hypothesis. A null and alternative hypothesis are often expected in statistics-based work.
Methods
Give enough detail for another student to repeat the experiment: materials, concentrations, equipment, sample sizes, controls, variables and how measurements were taken. Write it as connected prose unless your manual allows a list.
Results
Present data in labeled tables and graphs, with units. Describe the main trends in words, and report statistics such as means, standard deviations and test results. Save explanation for the discussion.
Discussion
Say whether the results support the hypothesis, explain why using theory, compare with published findings, and evaluate sources of error and their effect. Suggest realistic improvements.
Tense and Voice
- Methods: past tense. Many courses still prefer the passive voice, as in "The samples were incubated at 37 °C for 30 minutes."
- Results: past tense for what you observed; present tense for what a figure shows.
- Introduction and discussion: present tense for accepted theory; past tense for what earlier studies found.
Some departments now accept the active voice ("We incubated the samples"). Follow your lab manual or tutor's guidance.
Step by Step
- Read the lab manual and marking scheme before you start writing.
- Organize your data and run any required calculations or statistical tests.
- Draft the methods while the practical is fresh in your mind.
- Build tables and figures, then write the results around them.
- Write the discussion, linking every claim to your data or a source.
- Write the introduction, so it sets up exactly what the discussion addresses.
- Write the abstract and title last.
- Check figures, units, significant figures and references.
Example Results and Discussion Excerpt
Results. Mean oxygen production increased from 2.1 cm³ per minute at 10 °C to a peak of 6.8 cm³ per minute at 40 °C, then fell sharply to 1.4 cm³ per minute at 60 °C (Figure 1). Variation between repeats was greatest at 50 °C.
Discussion. The rise in activity up to 40 °C supports the hypothesis that higher temperature increases the rate of enzyme-substrate collisions. The sharp fall above 40 °C is consistent with denaturation of catalase. The wide spread of repeats at 50 °C suggests the water bath struggled to hold a stable temperature, which may have affected the exact position of the optimum.
Illustrative figures for a fictional practical.
Notice that the results report numbers and trends only, while the discussion explains them and weighs a specific source of error.
Tables and Figures That Do Their Job
Tables and graphs often carry the most marks in the results. A few conventions make them clear at a glance.
- Number and title every one, such as "Table 1. Mean oxygen production at each temperature".
- Table titles go above the table; figure captions usually go below the figure.
- Label axes with the quantity and unit, such as "Temperature (°C)".
- Choose the right chart: a line graph for continuous variables, a bar chart for categories.
- Show variability, such as error bars, when your manual asks for it.
- Refer to each one in the text, so the reader knows why it is there.
Common Mistakes
| Mistake | Fix |
|---|---|
| Interpreting data in the results | Move explanation to the discussion |
| Graphs without labels or units | Label axes, include units and number each figure |
| Vague error analysis, such as "human error" | Name the specific source and its likely effect |
| Methods written as a recipe list | Use clear prose unless told otherwise |
| Hypothesis missing or untested | State it in the introduction and answer it in the conclusion |
Lab Report Checklist
- Informative title naming the variables.
- Abstract with numerical results.
- Clear aim and hypothesis.
- Methods detailed enough to repeat.
- Labeled tables and figures with units.
- Discussion that interprets, compares and evaluates error.
- Conclusion that answers the aim.
- References in the required style.
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Frequently Asked Questions
Most follow title, abstract, introduction, methods, results, discussion, conclusion and references, sometimes with appendices.
Many courses prefer passive voice in the methods, but some accept the active voice. Follow your lab manual.
Results present the data without explanation. The discussion interprets the data, compares it with theory and evaluates error.
It depends on the course. Check your manual for word limits and required sections.
Usually yes, for background theory and for comparing your results with published findings.
Raw data, extra calculations or long tables that support the report but would interrupt the main text.
No. We work from the data you collected and never invent results.