This paper reports part of a research programme on physics curriculum development. Here, we look at the ways students choose relevant factors in two practical problems; define strategies to test them; and plan data collection in the school laboratory. Individual written investigation plans provided data about 73 physics students from three classes at grade 11. We look at the relevant independent variables identified, explanations adopted by students and the quality of their plans. Analysis indicates that more than half of the students have satisfactory knowledge of how to control variables in the context of a simpler problem (P2). However, in a more complex situation (P1), this figure drops to about 1/3. We suggest that students need more teacher support in their efforts to develop their scientific reasoning. It becomes clear the importance of a balanced curriculum, based on traditional as well as on open practical activities.
Physics teaching; practical problem solving; investigation plans
