How many are talking? The role of collectivity in dialogic teaching

•The effects of the implementation of dialogic teaching are examined.•An increase in the amount of student talk with thought and reasoning was observed.•A positive relationship between the number of students participating and the quality of student talk was found.

This study deals with the impact of a teacher development program focused on the implementation of dialogic teaching practice. The participants were eight Czech teachers in lower secondary schools and their classes. An analysis of video recordings of their lessons made during a one-year action research program revealed that classroom discourse had changed. Students had started to participate in a more productive way, which led to an increase in complex student talk characterized by thought and reasoning. In this study, we pose the question whether there is a relationship between the quality of student talk and the number of students participating in classroom discourse. Our analysis shows that the greater the number of students who participate in communication, the higher the probability that elaborated student talk with thought and reasoning will occur. However, this relationship is not a direct one; it is induced by a mediating variable constituted by the duration of open discussion.