This paper deals with the functions of drawing & writing practices as a mean for young children (age 4/5) to engage into school forms of culture (Schubauer-Leoni, Leutenegger & Forget, 2007). A didactical design (Peres, 1984; Brousseau, 2004), involving the construction of a shared convention for designating a set of small familliar objects was implemented over several months in two distinct educational contexts, namely Switzerland - Geneva canton and France. In both cases, the teaching actions are analysed with respect to certain epistemological norms for coding the objects into a system of signs, either rooted in mathematical logics (symbols) or in linguistic forms (words). The comparison of teaching practices in both educational contexts allows to delineate the epistemic specificity of the teaching practice that is supported by the didactical design and the generic dimensions of the teaching practice that is related to the institutional frame. We claim that a comparative approach of the teaching practices across educational contexts unveils the co-determinants of the early disciplinary forms of culture being construed in the classroom.