Planning Investigations and the Practical Endorsement

State the independent variable you will change and the dependent quantity you will measure. Identify controls by explaining how each could affect the result. A hypothesis should predict a relationship, not merely say that something “changes”. Choose a range wide enough to test it and an interval small enough to show the trend.

Translate the model into an expected graph and gradient before collecting data. For example, testing pendulum T² against length makes the gradient 4π²/g. That tells you which quantities need accurate measurement and why timing several cycles is helpful.

Specify the apparatus, its arrangement, a consistent reference point and the sequence of readings. Use a pilot trial to choose suitable ranges, avoid saturation and estimate the dominant uncertainty. Repeat independent measurements where they assess random variation; keep raw data and units rather than only a final average.

Identify concrete hazards, who could be harmed and the controls used in the centre’s approved procedure. A vague instruction to “be careful” does not address a hot wire, falling load or laser beam. Explain checks for zero error, calibration drift and control-variable stability.

The written papers assess planning, implementing, analysing and evaluating experimental evidence. The separate Practical Endorsement is based on teachers observing competence and records across at least 12 assessed activities covering the required skills and techniques.

OCR’s Practical Activity Groups help organise suitable activities; they are not the same as AQA’s fixed list of 12 required practicals. Centres can choose activities that provide the necessary coverage. Reading a lesson or passing its quiz cannot itself award the endorsement. Keep a clear contemporaneous record of your own work and reasoning.

Try each problem before opening the worked solution. State the physical model, show substitutions with consistent units, and explain what your answer means.