The question addressed in the present article concerns the contextual character of students’ conceptions of cases of psysical motion. An interview investigation with students following the mechanical engineering line of study at Chalmers University of Technology, Goteborg, Sweden was carried out during the students’ first year of study, before and after their first course in Mechanics. In the interviews, the students were verbally presented with eight cases of physical motion, four before and four after the course. The analysis of the conceptualization of physical motion points clearly to the very restricted contextual character of the conceptions of the cases. In previous research, the tradition of describing thinking and knowledge in terms of cognitive structures, shemas, models and so on, is very dominant. In relation to our results, one problem with the focus on cognitive structures is the assumptions made about generality across case or instances. Also, the students’ starting-point for their reasoning about the cases is not in any conceptual framework but in the specific cases. The conceptualizations are related to the students’ previous experiences rather than to any clearly delimited and structured conceptual framework.