Description: From the didactic point of view the need emerges for identifying the teaching objects in their relations with the reference practices, with a widening of the artistic educative project which, in addition to the expressive dimension, includes today communication and semiopragmatic designs (Peraya & Rickenman, 1998; Rickenmann, 2001). From this point of view, the uses of cultural institutions become a major referent for the production of didactic environments: knowledge relating to a cultural object is not considered any more independently of the social practices in which they are mobilized or used. The diversification of contents and objectives of programmes, with the increasing importance of the social mission of transmission of the inheritance, thus goes hand in hand with a diversification of the types of activities and roles which are proposed to pupils. From the study of teaching/learning sequences centered on the use of the inheritance exposed in Genevan museums (Museum of art and history, Cabinet of prints, MAMCO), this contribution will question the links of mutual determination which are woven between logics and expertises suitable for social practice "to visit an exposition" and the learning tasks which are inspired from it. The study will show how systems of reference enrichment, with the taking into account of social practises related to reception of works, produced among teachers important modifications in their approach of didactic environments suggested to students (mesogenetic dimension of teaching) as in didactic functions they allot to the student's activity (topogenetic dimension). It will also show how cultural objects and related practices are in their turn transformed by the didactic activity.