Planning & Evaluating Experiments — A-Level Physics Revision

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What is Planning & Evaluating Experiments?

This topic focuses on the higher-level skills of experimental design and critical analysis. It involves formulating a testable hypothesis, designing a safe and effective experimental procedure to investigate it, and identifying the key variables to control. A crucial part of this process is evaluating the completed experiment by identifying the main sources of uncertainty and suggesting specific, realistic improvements to the method or apparatus to enhance its accuracy and precision.

Board notes: Planning and evaluation are high-level skills tested in all A-Level Physics specifications (AQA, Edexcel, OCR), particularly in the written papers that assess practical skills. Questions often present a student's experimental method and require candidates to critique it and suggest improvements. These skills are developed throughout the course via the required practical activities.

Worked example

Common mistakes

• 1Proposing a vague or untestable hypothesis. A good hypothesis must be a clear statement that predicts a relationship between an independent and a dependent variable.
• 2Failing to identify and control all significant variables. A valid experiment must only have one independent variable; all other factors that could affect the outcome must be kept constant.
• 3Suggesting generic or unrealistic improvements. For example, simply saying 'use better equipment' is not a valid evaluation point. A good suggestion would be 'use a micrometer instead of a ruler to measure the wire's diameter to reduce the percentage uncertainty in the cross-sectional area'.

Planning & Evaluating Experiments exam questions

Exam-style questions for Planning & Evaluating Experiments with mark-scheme style solutions and timing practice. Aligned to AQA, Edexcel and OCR specifications.

Frequently asked questions

• What makes a good experimental plan?

  A good plan includes a clear diagram of the apparatus, a step-by-step method, identification of independent, dependent, and control variables, a description of how data will be collected and analysed (e.g., by plotting a graph), and a risk assessment identifying hazards and precautions.

• How do you evaluate the validity of an experiment?

  To evaluate validity, you must consider whether the experiment truly tests the intended hypothesis. This involves assessing how well control variables were kept constant, whether there were significant systematic errors, and if the measurements taken were appropriate for the conclusion being drawn.