Abstract
In recent years, several studies have highlighted the importance of tackling the students’ difficulties in understanding of the concept of the integral. This study carried out with the first year students of the Mathematics Degree at the Universidad Complutense de Madrid, presents a deeper insight into these difficulties through data collected from a non-routine problem questionnaire and semi-structured interviews. Some of these difficulties clearly have their origin in the coordination between the analytic and graphic registers. In the analysis of students’ use of the graphic register, the distinction between two different functions of images (iconic and heuristic) is exploited productively. Moreover, a specific teaching of visualization is recommended. As a main contribution in this approach two examples of relevant characteristic of visualization that should be taken into account in this proposal are shown: a high cognitive requirement and the need of a global apprehension.