IGCSE Physics / Practical and maths skills
Planning an investigation: variables and fair tests
Edexcel International GCSE Physics (4PH1), chapter 29: Practical and maths skills, specification point 1.5, 2.9, 5.4. Part of the full course.
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An investigation is a fair test when you change one variable, measure how another responds and keep other relevant variables the same. Clear methods name the apparatus and explain how you will collect, repeat and use the results.