In this paper we show how modelling appears as a federating transversal theme for mathematics and sciences in the new curriculum for all compulsory education in French speaking Switzerland. We then present a training course for in-service teachers we have set up on this theme for all mathematics teachers in Geneva's lower secondary schools, in relation with the European project PRIMAS . Based on a broad definition of modelling, we introduce a typology in three levels of modelling activities. Finally, we show how this was used in this training course in order to classify and analyse a few activities in relation with modelling in the new mathematics textbook for grade 7.