The three question types
Paper 6 typically has three questions:
- Planning question: design an experiment to test a hypothesis. Must include: variables, range of values, method, controls, how results are recorded, how to use results to reach a conclusion.
- Data analysis question: given a table or graph, draw a further graph, describe trends, calculate values, and draw conclusions.
- Evaluation question: given an experimental method, identify sources of error, suggest improvements, and assess reliability.
Planning experiments
Use this checklist for every planning question:
- State the independent variable (what you change) and give 5+ values
- State the dependent variable (what you measure) and how you measure it
- List controlled variables and how to keep each constant
- Describe a numbered method that another student could follow
- Include repeats and calculation of a mean
- State a safety precaution if relevant
- Describe how to use the results to answer the question
Analysing data and graphs
When drawing a graph from data:
- Choose an appropriate scale that uses most of the grid
- Label both axes with variable name and unit
- Plot points accurately
- Draw a line of best fit (smooth curve or straight line, not dot-to-dot)
When describing trends: state the overall pattern, quote specific data points, and identify any anomalous results.
Evaluating methods
Identify sources of error (things that could make results inaccurate) and suggest improvements. Common evaluation points include:
- Sample size too small → increase repeats
- Variable not controlled → describe how to control it
- Measurement imprecise → use a more accurate instrument
- Observer bias → use objective measurement (e.g. Colorimeter instead of visual colour comparison)