There is no agreement about the robustness of intuitive representations of the circulatory system and their susceptibility to change by instruction. In this paper, we analyse to what extent students with varying degrees of biology instruction and different ages (High School Health Science and Social Science students and first and final year…

Students' conceptions of the concept of force are discussed. Possible problem formats and exercises are presented. The need for many formats and variations to help students' resolve their conflicting ideas about physics concepts is stressed. (CW)