This article presents the results of a research done with two chemistry teachers of secondary schools. Based on observation and on registering classes, we analyzed verbal interactions amongst teachers and students around experimental activities and the tasks that followed them. We used a sociologic perspective from Basil Bernstein to analyze our data, which allowed us to contrast the teaching in two socially different school contexts. The results pointed out those pedagogic practices were most favorable to intervention of students and to production of the requested tasks. We noticed that the students submitted to a practice which teacher has a greatest control over communication had fewer chances to intervene during the activities and also a poorest instruction than students that had a major freedom during interactions with their teacher.
Discursive interactions; Pedagogic practice; Experimental activities.
