This paper reports on an educational design research study exploring the potential in combining the teaching of entrepreneurial and mathematical competences in Swedish primary schools. The focus in this paper, however, is not on the wholeness of this study but on changes in the teacher role when entrepreneurial and mathematical competences are to be combined in teaching – as expressed by the teachers themselves. Two of these expressed changes are “saying less” and “daring to let go of control”. In the paper, these two changes are explored in relation to how they seem to influence these teachers’ teaching of mathematics, and some implications are drawn regarding how their students’ possibilities to learn mathematics may have been influenced.