Abstract
The aim of this paper is to introduce and present one of the negative effects of implementing a dynamic mathematics program in a mathematics class. The Jourdain effect, as discussed in the theory of didactic situations, is illustrated on two experiments with seventh- and ninth-graders.
The study shows when and how this phenomenon occurs and how best deal with it (or better yet, avoid it). The experiments further show the importance of a teacher’s role in these specific technology-supported lessons as that of an “inconspicuous guide” who chooses appropriate tasks for their pupils and guides them with effective good questions.