A school, rather than a researcher, changes lesson length. Researchers compare concentration before and after the change. Identify the type of experiment and explain one strength and one weakness.
139 exam-style questions on OCR GCSE Psychology 7.2 Doing Research, covering 7.2.1 Experiments, 7.2.2 Interviews, 7.2.3 Questionnaires (Surveys), 7.2.4 Observations, 7.2.5 Case Studies, and 7.2.6 Correlations. Each one has a worked solution and a mark scheme showing where the marks go.