How to Write a Lab Report: Full Structure, Section by Section

A lab report is a scientific report of an experiment you carried out: what you set out to test, how you tested it, what you found, and what it means. It is not an essay and not a diary of your afternoon in the lab — it is a structured account that another student could read and, in principle, repeat.

That word — repeat — is the key to what markers want. A strong report is clear enough that someone else could follow your method and get comparable results. Markers are really checking four things: that each section does its job, that your method is described precisely enough to be replicable, that your data is presented cleanly, and that your discussion turns those results into analysis rather than just repeating them.

None of this has to be worked out alone. If a science or engineering write-up is hard to structure, My Perfect Writing’s environmental science assignment help and engineering assignment support can help you understand what a strong report looks like in your subject — the aim is always to help you write your own, not to write it for you.

Integrity first A lab report describes work you actually did and data you actually recorded. Plan it, structure it and review it — but the experiment, the results and the writing must be genuinely yours.

Most lab reports follow the IMRaD structure — Introduction, Methods, Results and Discussion — a standard scientific reporting format wrapped with a title, abstract, conclusion and references. Always check your module brief, but the standard order is:

• Title — what the experiment investigated.
• Abstract — a short summary of the whole report.
• Introduction — background, aim and hypothesis.
• Methods (Methodology) — what you did, in enough detail to repeat.
• Results — your data, in figures and tables.
• Discussion — what the results mean.
• Conclusion — the short, direct answer to your aim.
• References — the sources you cited, in your required style.

The rest of this guide takes each section in turn. If you only remember one rule, make it this: every section has a job, and marks are lost when one section starts doing another section’s work.

The title should say what was investigated, specifically. “Enzyme experiment” tells a marker nothing; “The effect of temperature on the rate of an enzyme-controlled reaction” names the variables and the relationship you tested.

The abstract is a short summary of the entire report — usually 150–250 words — covering the aim, method, main result and main conclusion in a few sentences each. Even though it appears first, it is easiest to write last, once you know what the report actually says. A common mistake is treating the abstract as an introduction; it is a miniature of the whole report, results included.

The introduction sets up the experiment. It gives just enough background theory to make the study make sense, states the aim (what you were trying to find out), and sets out your hypothesis — your testable prediction about how the variables relate.

Keep the background focused: you are framing this experiment, not writing a full literature review. A good introduction usually ends with a clear aim or hypothesis so the reader knows exactly what the rest of the report is testing. Where you draw on theory or prior studies, cite them — the details go in your references section.

The methods section explains what you did, in enough detail that someone else could repeat the experiment and expect similar results — this is what replicability means in practice. Include the materials, the procedure, and how you controlled and measured your variables (independent, dependent and controlled).

Write it in the past tense, because the work is already done, and usually in the passive voice (“the solution was heated to 40 °C”) unless your brief says otherwise. Describe what you did — not a list of instructions to the reader. The classic failure here is a method so vague (“we heated it for a bit”) that no one could reproduce it.

The results section presents your data — and only presents it. Use figures and tables to show your findings clearly, label each one and give it a number, and refer to them in the text (“as shown in Figure 1”). A short sentence pointing out the main trend is fine; a full explanation of why it happened is not — that belongs in the discussion.

Any calculations or basic data analysis (means, ranges, simple statistics) sit here too, presented cleanly. Like the methods, results are written in the past tense. The single most common error is interpreting your data in this section — keep “what happened” here and save “what it means” for later. If you are not sure which side of that line a sentence sits on, Marker’s Eye can review your own draft against UK marking criteria and flag where reporting should become interpretation.

The discussion is where the marks are won or lost, because it is where you stop reporting and start interpreting: what your results mean, whether they support your hypothesis, how they compare with existing research, and what their limitations are.

It is a big topic, so we have given it its own guide rather than repeat it here. For the full breakdown — the six moves of a strong discussion, an annotated example, and how to handle unexpected or negative results — read how to write the discussion section of a lab report. If you find your discussion keeps slipping back into description, our guide on description vs analysis: what markers want shows exactly where the line sits.

These three sections trip students up more than any other, because they all deal with “the findings” — but each handles them differently. The results report the data, the discussion interprets it, and the conclusion answers the aim in a sentence or two. The table below shows what belongs where, and what markers are looking for.

References. Any theory, background or prior study you mention must be cited in your required academic referencing style — Harvard, APA, Vancouver or IEEE are all common, so follow your department’s guide and stay consistent throughout. If you are weighing up two systems, our guide to Oxford vs Harvard referencing explains how each one works in practice.

Formatting. Number every figure and table and refer to them by number; keep tense consistent (past tense for what you did and found, present tense for established facts); and use clear section headings so a marker can navigate at a glance.

Length. There is no universal word count — a lab report is as long as it needs to be to report the experiment clearly, and your brief or rubric is the real authority. As a rough guide, undergraduate reports often run 1,000–3,000 words, with the abstract kept to 150–250. Precision beats padding: markers reward a tight, complete report over a long, repetitive one.

• Blurring results and discussion. Interpreting data in the results section, or re-listing data in the discussion, is the most frequent mark-loser.
• A method that can’t be repeated. Vague or incomplete methods break replicability — the reader should be able to follow your steps exactly.
• Unlabelled figures and tables. Missing numbers, titles or units make your results hard to read and cost easy marks.
• An abstract that isn’t a summary. Writing an introduction instead of a miniature of the whole report, results included.
• Weak analysis. Describing what happened without explaining why — the gap between a pass and a strong grade.
• Inconsistent referencing. Mixing citation styles or forgetting to cite the theory you relied on.

Not sure what belongs in each lab report section? Our Lab Report Structure & Discussion Workbook maps every section for you, gives prompts to turn your results into analysis, and lists what markers expect — so you can check your structure before you submit rather than after you get the grade back.

Grab the workbook Use the free resource card on this page to get the Lab Report Structure & Discussion Workbook sent to you — it’s built to sit next to your draft as you write.