The study investigates the roles of teachers in the knowledge schooling process, describing how it uses cognitive and material resources in the biology classroom. From Bernstein's idea of structuring the discourse, the class was considered as mediated by an official pedagogic discourse, analyzed as multimodal, subjected to rules set ideologically, but that varies with the context. The analysis of a speech during a class in which an exercise was corrected on the application of Mendel's laws showed the creative work of the teacher in school scientific knowledge. It also demonstrated that, in certain contexts of social interaction, the regulative discourse of social order legitimates the discursive order that guides the school in educational practice.
Schooling process; multimodal discourse; school pedagogical practices.