How to Write the Discussion Section of a Lab Report

The discussion is the part of a lab report where you interpret your experimental results and explain what they mean. The results section reports the data objectively — tables, figures, and observations — while the discussion explains why those findings matter and how they answer your research question.

A useful way to see the difference: the results section says what happened; the discussion says what it means — a distinction the IMRAD report structure makes explicit. It links your findings back to your hypothesis, connects them to the wider scientific literature, and judges how far your evidence supports each claim.

Results vs discussion If a sentence only states a value or trend, it belongs in your results. If it explains, compares, or evaluates, it belongs in your discussion.

Most high-scoring lab report discussions move through the same six moves, roughly in this order:

• Summary of key findings. Restate your main result in words and say whether it supports your hypothesis. Do not re-list every value.
• Interpretation of results. Explain the likely reason for the pattern you observed — the mechanism, trend, or relationship behind the numbers.
• Comparison with the literature. Show whether your findings agree or disagree with previous research, and offer a reason for any difference.
• Limitations and sources of error. Identify what could have affected your results — sample size, random error, or systematic error — briefly and specifically.
• Implications. Explain what the results mean for the topic, and whether any difference is meaningful (for example, statistically significant) rather than due to chance.
• Future research. Suggest a focused next step: a better method, a wider sample, or a follow-up question your data raised.

Here is a short, illustrative discussion for an experiment measuring how temperature affects an enzyme-controlled reaction rate. Each sentence is labelled with the element it performs.

Summary of findings The reaction rate rose as temperature increased up to 40 °C, then fell sharply, supporting the hypothesis that the enzyme has an optimum temperature.

Interpretation The initial rise is consistent with molecules gaining kinetic energy and colliding more often, while the drop above 40 °C suggests the enzyme began to denature and lose its active-site shape.

Comparison with literature This optimum is close to values reported for similar enzymes in previous studies, which strengthens confidence in the result.

Limitation / source of error Only three repeats were taken at each temperature, so random error may have affected the mean, and the water bath varied by roughly ±1 °C.

Implication & future research The pattern indicates temperature must be controlled carefully in this reaction; a useful next step would be to test smaller temperature intervals near the optimum to locate it more precisely.

Notice that no new raw data is introduced — every sentence interprets results already reported in the results section.

• Use the past tense for what you did and found (“the rate increased”), and the present tense for established facts.
• Write in a cautious, evidence-led voice. Prefer “the results suggest” or “this may indicate” over absolute claims — scientific writing hedges appropriately.
• Refer to figures and tables by number rather than repeating their contents.
• Stay concise and third-person unless your brief allows first person, and keep each paragraph focused on one idea.
• Introduce no new results — the discussion only interprets data already presented.

• Repeating the results. Re-listing every value instead of interpreting them is the most common way marks are lost.
• Being too apologetic. A long list of everything that went wrong reads as weakness — state limitations briefly and specifically.
• Introducing new results. Any data or figure must already appear in the results section; never invent or add data, in line with academic integrity.
• Overstating the findings. Do not claim more than your evidence supports; a single experiment rarely “proves” anything.
• Ignoring negative or unexpected results. Results that contradict your hypothesis are still valid evidence — credible scientific-writing guidance recommends acknowledging anomalous data rather than leaving it out.