Master the IMRaD structure — Introduction, Methods, Results, and Discussion — and write scientific reports that are precise, reproducible, and analytically convincing.
A lab report is a structured written account of an experiment or practical investigation — what you did, why you did it, what you found, and what it means. It is the primary genre of scientific communication at undergraduate level, and a direct precursor to the journal article format used by professional scientists.
The lab report serves several functions: it demonstrates that you can design or follow an experimental procedure; that you can collect, record, and present data accurately; that you can analyse results in relation to your hypothesis; and that you can discuss findings in the context of existing scientific knowledge. It is as much a test of scientific thinking as of laboratory technique.
Lab reports differ significantly from essays. Essays argue a position using evidence from sources. Lab reports report empirical observations using a standardised structure designed to make the work transparent and reproducible. The reader of a lab report should be able to replicate your experiment exactly from your Methods section — and should understand exactly what you found, and what you conclude, from your Results and Discussion.
The expectations for lab reports vary across disciplines (biology, chemistry, physics, psychology, engineering) and across levels (first-year undergraduate vs. final-year independent project). Always consult your module handbook or lab manual, and follow any discipline-specific conventions your instructor specifies.
Most lab reports follow the IMRaD structure — Introduction, Methods, Results, and Discussion — with a title, abstract, and reference list added. This is the standard structure of scientific journal articles and is deliberately designed to separate the different cognitive tasks: explaining context (Introduction), describing procedure (Methods), presenting data (Results), and interpreting findings (Discussion).
Some disciplines combine Results and Discussion into a single section. Some add a separate Conclusion. Some require a separate Materials section. Your lab manual will specify the required structure — follow it exactly.
A good lab report title is specific enough that a reader knows exactly what was investigated — including the key variables and the organism or system studied. Avoid vague titles that could apply to any experiment in the area.
The abstract is a self-contained summary of the entire report. A reader who reads only the abstract should understand: what was investigated, why, how, what was found, and what was concluded. Write it last.
A standard abstract covers: (1) the purpose/hypothesis, (2) the key methods (very briefly), (3) the main results (with key numbers/statistics), and (4) the main conclusion. Avoid citations, undefined abbreviations, and vague statements like "results were interesting."
The introduction moves from broad to specific — from the general scientific context to your specific experiment. It answers the question: why was this experiment done?
Hypothesis: "It was hypothesised that increasing light intensity would increase the rate of photosynthesis in Elodea, as measured by oxygen production, up to a saturation point."
Prediction: "It was predicted that as light intensity increased from 0 to 5000 lux, oxygen production would increase linearly."
Aim: "To determine the relationship between light intensity and photosynthetic rate in Elodea canadensis."
Not all reports require all three. Check your lab manual.
The Methods section must contain enough detail for another scientist to replicate the experiment exactly. Write in past tense, passive voice, and third person. Do NOT write it as a list of instructions ("Add 5 mL of HCl") — write it as a description of what was done ("5 mL of hydrochloric acid (0.1 M) was added…").
Cover the following sub-sections (if applicable):
If you followed a published or provided protocol, cite it — then describe any deviations from it. You do not need to rewrite a well-known standard protocol in full; a citation plus deviations is sufficient.
The Results section presents what you found — objectively, without interpretation or discussion of what it means (that comes in Discussion). It should include:
"The results showed that light intensity had a big effect on photosynthesis. As expected, more light led to more oxygen. This proves our hypothesis was correct."
Strong — precise, objective, quantified"Oxygen production increased significantly with light intensity from 0 to 3000 lux (r² = 0.94, p < 0.001). At intensities above 3000 lux, the rate of increase slowed, with no significant difference observed between 4000 and 5000 lux conditions (t(8) = 1.12, p = 0.295), suggesting saturation was approached (Figure 1)."
The Discussion is the most intellectually demanding section. It answers: what do your results mean? It should move through the following:
If a separate Conclusion is required (many labs include it as the final paragraph of Discussion), it should be brief — two to five sentences that: directly answer the aim/hypothesis, state the key quantitative finding, note the most significant limitation, and suggest implications or future work. Do not introduce new information in the Conclusion.
Scientific writing prioritises precision, clarity, and objectivity over stylistic elegance. Key conventions:
| Convention | Avoid | Use instead |
|---|---|---|
| Tense | Present tense for methods ("We add…") | Past tense ("5 mL was added…") |
| Person | First person ("I measured…", "We found…") | Passive voice ("Absorbance was measured…") |
| Vague language | "A big effect", "very significant", "interesting" | Quantified: "a 45% increase (p < 0.001)" |
| Hypothesis outcome | "The hypothesis was proven correct" | "The results support / are consistent with the hypothesis" |
| Units | "Temperature was 37 degrees" | "Temperature was maintained at 37°C" |
| Numbers | "Around five", "approximately ten" | Exact values with appropriate significant figures |
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