In this paper we describe a pre-service teacher professional development program based on Meta-Didactical Transposition model. We focus on the encounter between the praxeologies of researchers/teacher educators and pre-service primary teachers. We show how specific tasks for teachers and information provided by a standardized assessment database (GESTINV) can be used to establish a link between Italian National Evaluation System and pre-service teacher professional development. We present some aspects of mathematics specialized knowledge that pre-service teachers declare to be improved during the educational program. Pre-service teachers' reflections on their specialized knowledge are framed into MTSK model.