How to write a lab report that earns the marks

A lab report is marked on whether a reader could repeat what you did, see exactly what you found, and follow your reasoning about what it means. Structure is how you show all three.

Aim, background and hypothesis

State the aim in one sentence: what you set out to find or measure. Give just enough background science to explain why the experiment works and what you expect — a prediction with a reason, not a textbook chapter.

If your brief asks for a hypothesis, make it testable: name the variable you changed, the one you measured, and the direction you expect.

A method someone else could repeat

Write the method so that another student could reproduce your experiment without asking you anything: equipment with sizes and ranges, quantities, concentrations, times, temperatures, how many repeats, and how you controlled the variables you were not testing.

Check your brief for the expected style — many courses want past tense and passive voice ("the solution was heated"), some accept a numbered procedure.

Results: show, do not explain

Present the data clearly and keep interpretation for the discussion. Tables need headings with units; graphs need a title, labelled axes with units, a sensible scale, and error bars or uncertainties where your course expects them. Refer to every table and figure in the text.

Include processed data (means, rates, calculated values) and show one worked example of any calculation.

Discussion and evaluation

Explain what the results show and why, using the underlying science — this is where most of the marks usually are. Compare with what you expected and, if your brief asks, with published values.

Evaluate honestly: which sources of error mattered most, how they affected the results (in which direction), and what specific change would reduce them. "Human error" on its own earns little; "timing the colour change by eye probably made readings late, so rates are underestimated" earns marks.

Conclusion

Answer the aim directly in two or three sentences, with your key figure, and say whether the hypothesis was supported. No new information here.

Checklist before you submit

Aim stated in one sentence; hypothesis testable (if required)
Method complete enough to repeat, including repeats and controls
Every table has headings with units
Every graph has a title, labelled axes with units and a sensible scale
Results kept separate from interpretation
Discussion explains results with the science, not just describes them
Specific sources of error, their effect, and a specific improvement
Conclusion answers the aim with your key result
Referencing and format exactly as the brief asks

Common mistakes

Explaining results inside the results section, then repeating it in the discussion.
Graphs without units, or with axes that start in odd places without saying so.
Blaming "human error" instead of naming a specific, likely source of error.
A method written as a story ("then we tried...") that no one could follow.
A conclusion that summarises the method instead of answering the aim.

Check your own draft against your rubric

Paste your brief, your rubric and your draft report. The assignment helper checks each section against what your rubric rewards — method repeatable? results separate? errors specific? — and gives you the three fixes that matter most.

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Frequently asked questions

What sections does a lab report need?

Usually title, aim (and hypothesis), introduction or background, method, results, discussion, conclusion and references — but always follow the headings in your brief, which take priority.

Should a lab report be in the past tense?

The method and results are normally past tense because they describe what was done. Check your brief or handbook for the voice your course prefers.

Where do most lab report marks come from?

In most rubrics, the discussion and evaluation: explaining the results with the science and evaluating errors specifically. Look at your rubric weightings to see exactly where the marks are for your course.