This paper presents and uses the notion of configuration of activity, which extends the Norbert Elias's original concept of social configuration (1966) based on the study and analysis of individual and collective activity. Although this concept embraces all types of social activities, in the present study we used it to describe and analyze various classroom activities during a primary school mathematics lesson. Individual action is described as being meaningful to the agent, according to semiological theory of course-of-action (Theureau, 2003). The configuration of activity in the classroom is described as a collective activity with a global form embedded in a culture and emerging from the dynamics of points of articulation between individual actions. It presents the main characteristics of autonomous systems: (a) the emergence of an order, (b) the individuation of a form, (c) the existence of a unit with borders specified by the process of self-reproduction, and (d) the system sensibility to perturbation by outside events. Using the concept of the classroom configuration of activity, this study allows for new insights in the emergence of a teacher-pupils collaborative activity in the classroom.