Planning an investigation
A high-scoring plan turns a physical relationship into a repeatable sequence of measurements and analysis.
A strong plan links a testable relationship to measured quantities, controls, analysis and a valid conclusion.
By the end of this lesson, you can:
- state a testable relationship;
- identify the independent and dependent variables;
- describe a workable method;
- explain how results will test the relationship.
Begin with the model
Write the relationship to be tested and decide which quantity to vary and which to measure. A strong plan links every measurement to the final analysis.
A reproducible method
Name the apparatus, explain how it is arranged, state how each quantity is measured and describe a suitable range with at least six values where practical. Another student should be able to repeat the investigation.
Plan the analysis
Transform the proposed equation into y = mx + c form. State the graph to plot and explain how its gradient or intercept provides the required constant.
WORKED EXAMPLEReveal method
For T = 2π√(l/g), plot T² against l. The gradient is 4π²/g.
Try another worked problem
Attempt the question yourself, then reveal the examiner-style solution when you are ready.
Testable plan
For T²∝L, state a suitable graph and expected result.
CHECK YOUR ANSWERReveal solution
Plot T² on y against L on x; a straight line through the origin supports the relationship.
Mastery check
A complete experimental plan should state how the results will be: