Lab Report
To write: Give the report a specific title that names both variables, such as “The Effect of Light Intensity on the Rate of Photosynthesis in Elodea”.
Abstract
Tip: Write this section last. One paragraph, often 150–250 words — check your course's limit. Past tense for what you did and found, present tense for what it means.
To write: Summarize the aim, the method in a sentence or two, the key result with its numbers, and your conclusion.
Introduction
Tip: Present tense for established theory. Move from general background to your specific question, and end with the aim and hypothesis.
To write: Explain the science the experiment depends on — key concepts, equations, or earlier findings — and cite your sources.
To write: State the aim in one sentence: what you investigated, and in what system.
To write: Make a testable prediction with its reason: “If …, then … because ….”
Materials and Methods
Tip: Past tense, with enough detail for someone else to repeat the experiment: quantities, concentrations, equipment sizes, and the number of trials. Most university reports want prose here rather than numbered steps — check which your course expects.
Variables
To write: Name the variable you changed, with its unit and the values you used.
To write: Name the variable you measured, how you measured it, and its unit.
Controlled variables
To write: List what you kept the same, and how you kept it constant.
Materials
To write: List every item with its size, quantity, or concentration, in SI units (e.g. 250 cm³ beaker, 2.0 g sodium chloride).
Procedure
To write: Describe each step in the order you carried it out, including the number of trials.
Data analysis
To write: Explain how you processed the raw data: means, calculations (one worked example here or in an appendix), uncertainties, and any statistical test.
Results
Tip: Past tense, no interpretation — the why belongs in the Discussion. Number tables and figures in the order you mention them, refer to each one in the text, and give units in every column heading.
To write: Describe the main trend in words and give the key values — for example, the mean for each condition — pointing the reader to Table 1 and Figure 1.
| Independent variable (unit) | Trial 1 | Trial 2 | Trial 3 | Mean |
|---|---|---|---|---|
To write: Figure 1: plot the dependent variable on the y-axis against the independent variable on the x-axis. Label both axes with units, and add error bars if you calculated uncertainty.
Tip: Most science formats put a table's title above the table and a figure's caption below the figure; APA style puts both above. Follow your course's style, and put raw data or sample calculations in an appendix if they are required.
Discussion
Tip: Present tense to interpret, past tense to report your own results. Hedge your claims: one experiment supports or fails to support a hypothesis — it rarely proves one.
To write: Describe the trend and state whether the results support the hypothesis, quoting the key values.
To write: Explain the trend using the theory from your Introduction.
To write: Evaluate the method: name the main sources of systematic and random error, their likely effect on the results, and a specific improvement for each.
To write: Compare your results with published values or other groups' data, and cite your sources.
Conclusion
To write: In two to four sentences, answer the aim directly, say whether the hypothesis was supported, and give the key result with its number.
References
Tip: List every source cited in the Introduction and Discussion — including the lab manual if you relied on it — in your course's style (often APA, ACS, or CSE).
To write: Add your reference list here, ordered as your citation style requires.