Abstract
The aim of this paper is to understand and interpret the difficulties that students are facing when learning calculus during the transition from high school to university. We are specifically interested by the study of functions. We first discuss the general background concerning this transition and the notion of function. Then we define quite separate working domains, specific on the one hand of the high school practices and on the other hand of university practices. Finally, we present a study in which we examine the freshmen’s difficulties in calculus.