In the last years, the interest of mathematics educators in digital tools has progressively increased, having as consequence a great impact on how teachers plan their teaching activities. In this paper we investigate, by using the Meta-Didactical Transposition, if the peer review methodology, carried out in a blended course, can facilitate the teachers as instructional designers. The aim of the meta-didactical praxeologies put in action by the trainers was focused on the sharing and reflection with the teachers on a specific topic relative to the argumentative competence. A qualitative analysis of the educational activities produced by the teachers has shown that the peer review methodology enables the teachers to improve their role of the instructional designer.