How to Write a Lab Report

What Is a Lab Report?
IMRaD Structure Explained
Title & Abstract
Introduction
Materials & Method
Results
Discussion
Conclusion & References
Common Mistakes

What Is a Lab Report?

A lab report is a structured document that records the purpose, procedure, data, and interpretation of a scientific experiment. It serves two functions: it communicates your findings to others, and it demonstrates that you understand the scientific principles being tested.

Lab reports are required in biology, chemistry, physics, psychology, environmental science, and many engineering disciplines. Most follow the IMRaD structure — Introduction, Method, Results, and Discussion — the same framework used in published research articles.

IMRaD Structure Explained

Section	Core question it answers	Tense
Title	What was investigated?	—
Abstract	What did you do and find? (summary)	Past
Introduction	Why was this experiment done?	Present / Past
Method	How was the experiment conducted?	Past passive
Results	What was observed?	Past
Discussion	What does it mean?	Present / Past
Conclusion	What was learned and what comes next?	Present / Past

Title & Abstract

Title

A good lab report title is specific and descriptive — it identifies the independent and dependent variables and the system being studied.

Weak title

Enzyme Experiment

Strong title

Effect of Temperature on the Catalytic Activity of Amylase in Starch Hydrolysis

Abstract

The abstract (100–200 words) summarises the experiment's purpose, method, key results (with numbers), and main conclusion. Write it last. It must be self-contained — a reader should understand the study without reading further.

Introduction

The introduction provides the scientific context for the experiment. It should:

State the topic and scientific background — what is already known about the phenomenon?
Identify the specific research question or hypothesis — what gap does this experiment address?
State your hypothesis — a testable prediction, often in if/then form
Briefly justify the method chosen

Hypothesis example

If the temperature of the reaction environment is increased above the optimal range for amylase activity (approximately 37°C), then the rate of starch hydrolysis will decrease due to enzyme denaturation.

Write in third person

Most science disciplines require the passive voice and third person: "The hypothesis was that…" rather than "I thought…" Check your module handbook, as conventions vary.

Materials & Method

The method section allows any qualified scientist to replicate your experiment exactly. Write it in the past tense, passive voice, and with sufficient detail to enable replication — but avoid unnecessary procedural narrative.

Include:

Materials/Equipment list — all chemicals, instruments, concentrations, brands where relevant
Procedure — step-by-step, organised chronologically; use numbered steps or continuous prose depending on discipline
Controls and variables — identify independent, dependent, and controlled variables
Sample size and repetitions — note how many trials or samples were used
Safety precautions — if required by your institution

Do not copy the lab manual verbatim

Write the method in your own words as a description of what was actually done — including any deviations from the original protocol. If your procedure differed from the lab sheet, document that clearly.

Results

The results section presents data without interpretation. Include:

Raw and processed data in clearly labelled tables
Graphs and figures with captions and labelled axes (units required)
Statistical analysis where required: mean, standard deviation, t-test, ANOVA, p-values
A brief narrative summary directing the reader to key trends — but no explanation yet

Results narrative example

Table 1 shows the mean absorbance readings at each temperature. Amylase activity peaked at 37°C (absorbance = 0.82 ± 0.04) and declined sharply above 55°C, reaching near-zero activity at 75°C (0.09 ± 0.01). Figure 1 illustrates this bell-shaped curve.

Every figure and table needs a caption

Tables: caption above ("Table 1: Mean absorbance values…"). Figures: caption below ("Figure 1: Effect of temperature on amylase activity…"). Number them separately and sequentially.

Discussion

The discussion is where you interpret the results. It is usually the longest and most intellectually demanding section. It should:

Restate whether your hypothesis was supported or rejected — explicitly
Explain the results in terms of scientific theory: why did you observe what you observed?
Compare with published literature — do your findings match established knowledge? If they diverge, why?
Identify sources of error — systematic errors (flawed design) and random errors (variability); assess their likely impact
Suggest improvements — what would a better-designed experiment look like?
State implications — why do these findings matter?

Conclusion & References

Conclusion

The conclusion (1–2 paragraphs) concisely restates the hypothesis, confirms whether it was supported, summarises the key findings, and acknowledges major limitations. It does not introduce new information.

References

Cite all sources mentioned in your introduction and discussion. Most science disciplines use either APA 7, Vancouver (numbered), or the journal's own style. Check your module guide.

Common Mistakes

Mistake	Fix
Discussing results in the Results section	Results = data only; save interpretation for Discussion
Writing "I" or "we" (in disciplines that forbid it)	Use passive voice: "The solution was heated to…"
Graphs without labelled axes or units	Every axis: label + unit in parentheses e.g. Temperature (°C)
Vague error analysis ("human error")	Name specific errors: pipetting tolerance ±0.05 mL, timing delay
Hypothesis missing from introduction	State a clear, testable if/then hypothesis
Conclusion that just repeats the abstract	Conclusion focuses on what was learned and what should happen next

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