The proposed contribution will focus on the opportunities to influence professional competences of future primary mathematics teachers through experiencing inquiry based mathematics education (IBME). We understand teachers’ professional competences to be an amalgam of skills future teachers should master in order to be able to perform their first steps teaching. We consider that the key to professional competence is the subject didactic competence combining content knowledge, its didactical treatment and application of this knowledge in practice. The concept could be compared with PCK. Using the word “competence” we would like to stress the ability to act. The contribution will describe the results of a study aimed at the use of IBME in the training of future primary school teachers. The study contained: (1) Clarifying the concept of IBME in the Czech context. (2) Analyzing how students are able to use their knowledge of mathematics in elaboration of particular learning environment (number triangles) for IBME, that is how students are able to transform their knowledge into the subject didactic competence.