In this paper we present a case study, as part of a monitoring of beginning teachers’ classroom practices. Among other aspects, we have observed that, in such practices, Algebra intervenes in the other fields, to an extent that they induce in their students a Mathematical Working Space in which, although circulations occur between the components of the cognitive and epistemological planes involved in the instrumental and semiotic geneses, the discursive genesis is almost absent. In order to study the situation, we obtain additional information in such a way to understand the role played by algebra in the development of other fields of mathematics. We then present an example of how a beginning teacher with those characteristics can influence the personal Mathematical Working Space of his/her students.