How to write the discussion section of a lab report
A discussion explains what your results allow you to conclude. Start with the experiment question and your actual observations. Then show how the evidence supports your answer and where the method leaves uncertainty. Follow the structure your teacher asks for if it differs from the approach below.
Choose the result that answers the question
Put the question, results table and method beside your draft. Write one sentence answering the question as far as the results allow. Choose a comparison, trend or calculated value that supports it, with units. You do not need to repeat every measurement already visible in the results section.
Check the individual readings as well as any average. Do repeated trials show a similar pattern, or does one unusual reading account for much of the difference? Keep unusual results visible and investigate them. Remove a reading only when there is a justified reason, and explain that decision according to the assignment instructions.
If you made a prediction, compare it with the result. A result that disagrees with the prediction still belongs in the report. Explain the disagreement using the evidence you have, rather than rewriting the prediction or changing the measurements.
Explain the pattern without filling gaps with guesses
Connect your observation to a relevant idea from the lesson or a source you can cite. Say how that idea could account for the pattern. Keep the measured result distinct from the proposed explanation: the table may show a difference without establishing the mechanism behind it.
For each limitation, name the part of the method involved and how it could affect the comparison. “Human error” gives the reader little to assess. “The start and stop decisions depended on watching each drop, so timing could vary between trials” identifies an actual source of uncertainty. Do not claim it made all times too long or too short unless you have evidence for that direction.
A discussion paragraph built from example data
Consider a fictional investigation asking which of two paper helicopter designs stays in the air longer when released from the same height. Design A has recorded fall times of 1.1, 1.2 and 1.3 seconds; design B has 1.4, 1.5 and 1.6 seconds. The means are 1.2 seconds and 1.5 seconds. Suppose the example method used a handheld stopwatch and only one helicopter of each design. These measurements and method details are invented for this writing example.
A discussion could begin: “Design B had a mean fall time of 1.5 seconds, compared with 1.2 seconds for design A, a difference of 0.3 seconds. Each recorded B time was longer than each A time, so these trials support B staying in the air longer under the tested conditions. However, only one helicopter of each design was tested. A difference in how those two specimens were folded could have contributed to the result. Timing also depended on the observer deciding when the drop began and ended, so the measurements do not establish the size of the difference precisely. Testing several independently made helicopters of each design and using a consistent timing method would help check whether the pattern persists.”
This paragraph answers the question, gives numerical evidence and connects two limitations to specific follow-up actions. It does not explain why B fell more slowly. For a real report, add a supported explanation from the relevant lesson material, and use only limitations that apply to the method you actually followed.
Make improvements serve a specific purpose
Pair each suggested change with the uncertainty it addresses. Testing more separately made specimens checks whether the result depends on a single specimen. Keeping the release height and release procedure consistent helps make the trials comparable. More repeats can reveal variation, but they will not fix a measuring instrument that consistently reads incorrectly.
Use this planning template before drafting: “Answer to the question: [limited claim]. Evidence: [values and units]. Explanation: [relevant idea and source]. Limitation: [method detail and possible effect]. Improvement: [change and what it would help check].” Leave a field unresolved if you need to check your notes or ask your teacher; a complete-looking template is no reason to invent an explanation.
Read the finished discussion against your table and method. Check every number, make sure each proposed cause has support, and keep the conclusion within the conditions you tested. If the evidence is mixed or too limited for a clear answer, say so and identify what a further test would need to resolve.
