Lab report structure
A typical lab report has a title, abstract (if required), introduction or aim, materials and method, results, discussion, conclusion and references. Some courses add appendices for raw data and calculations.
Departments and courses vary, so follow your lab manual for headings and format. The report should let another person understand what you did, what you found and what it means, and in principle repeat the experiment.
Aim and hypothesis
State the aim in one or two sentences: what you were investigating and why. Give a short background with the relevant theory, and cite sources.
If the experiment tests a prediction, state the hypothesis clearly, for example: "If the temperature increases, the reaction rate will increase." A good hypothesis is testable and links variables, so identify the independent, dependent and controlled variables.
Method and materials
List the materials, equipment and settings, with quantities and specifications. Describe the procedure in past tense and passive or active voice as your department prefers, in enough detail for someone to repeat it.
Include safety precautions where relevant. A labelled diagram of the setup is helpful. Describe any changes you made to the original instructions and why. Do not write the method as a list of commands; write what was done.
Results: tables and graphs
Present data clearly with tables and graphs. Give each table and figure a number and caption, and include units and uncertainties where relevant. Show a sample calculation and put full raw data in an appendix.
Choose the graph type for the data: scatter plots with trend lines for relationships, bar charts for categories. Label axes with variable names and units. In the text, describe the main patterns, but save the explanation for the discussion.
Discussion and error analysis
Interpret your results: do they support the hypothesis, and how do they compare with theory or published values? Calculate percentage error where appropriate.
Analyse sources of error: systematic errors (such as an uncalibrated instrument) and random errors (such as reading variation). Explain how each might have affected the results and suggest improvements. Avoid vague statements like "human error"; be specific about what happened and the effect.
Conclusion
State whether the aim was achieved and summarise the main finding, with key values. Link it to the hypothesis. Keep it short, and do not introduce new data.
You can add one or two suggestions for further work, such as testing a wider range of conditions or using more precise equipment.
Checklist
Before submitting, check that:
- The title and aim are clear.
- The method is repeatable.
- Tables and graphs are numbered, labelled and have units.
- Calculations are correct and shown.
- The discussion addresses errors and limitations.
- The conclusion answers the aim.
- Sources are cited and listed.
- Your report follows the lab manual and has been proofread.