The purpose of our research is to question the epistemological issues of information culture and the place of SNSs in a school context. Through the prism of prescribed and informal information practices on NSRs, the aim is to study how a multi-layered and stratified information culture is being formed.Juvenile information practices on SNSs, which are divided between sharing and searching for information and communication between peers, question the documentary pedagogy implemented by teacher-librarians, who are responsible, within the school, for Media and Information Education.What are the links between prescribed documentary practices and informal juvenile practices? How do teacher-prescribed documentary pedagogical practices influence juvenile informal information practices on SNSs? What forms for information culture centred around SNSs? To answer these questions, we have implemented a comprehensive methodology combining interviews and observations of sessions and mobilizing analysis of speeches and pedagogical documents. Through the prism of prescribed information learning, one can observe that an information culture is emerging that is moving towards a critical approach to information taking the form of operational and conceptual information literacy education and shaping a culture of information citizenship.