The construction of a broad European research community about didactics raises the interests - but also the methodological problems – that are related to the comparison of theories and methods used to account for teaching and learning processes according to different research traditions (Hudson & Schneuwly, 2007). Comparisons of elaborated theories and methods may hardly be operated at a general level because of the specificity of the content embeded in the teaching and learning practices. This symposium aims at developing the potential of comparative approaches in didactics as a mean to overcome the scattered insights of teaching and learning practices across school disciplines and institutional frames. The claim is twofold: 1) on the one hand, describing and understanding the logics of teaching and learning practices cannot be achieved without accounting for the epistemic necessities at stake in classroom transactions; 2) on the other hand, the study of these practices cannot be reduced merely to the internal logic of the subject matters as defined by school and / or academic institutions. Comparative didactics attempts to move upward from the mere analysis of the subject matter being construed in the classroom, towards a more comprehensive model of the didactical transactions incorporating the continuity of the experience of the teacher and the students as selves (Dewey 1938). From the peculiar enactments of the ordinary teaching and learning practices, comparative didactics aims at delineating both the specific and the generic patterns of teaching and learning actions (Mercier, Schubauer-Leoni & Sensevy, 2002). This proposal explores the institutional "boundaries" in which teaching and learning processes are enacted. Typically, disciplines and curriculum frames delineate boundaries in the teaching and learning practices, but also the schooling organizations and the socio-political educational contexts. In the teacher's work, what techniques are specifically related to the epistemic norms of the knowledge content? What ways of doing are inherited from institutional norms and values about teaching and learning subject content? How does the knowledge being construed in the classroom may be impacted?. Paper 1 and 3 investigate the institutional frames of teaching and learning, in contrasting either the norms of the educational context at pre-school (Paper 1) or the selective traditions that are sedimented in the background of the science curriculum (Paper 3). Methodological devices require accounting for the temporal dynamics of the teaching and learning transactions. Sets of clinical evidences are gathered at different time scale of the course of classroom actions, in order to fuel an experimental process of comparison among scales (Schubauer-Leoni & Leutenegger, 2002). However, comparative research in didactics is not limited to contrasting some empirical observations; it also encompasses an investigation the compatibilities among of the theoretical framework being used, in terms ofepistemological foundations rooted in social sciences. Paper 2 bridges the teaching and learning practices that are traditionally nested in distinctive disciplines being taught at school (mathematics and sports) in order to feature generic patterns of the teacher and the student's joint action.