Classrooms (but also corridors and schoolyards) constitute an ecological niche where many conducts and interrelationships among persons take place. They must be ruled by a set of norms and habits that may end having different functions: favour coexistence, determine rules for the good working of the whole collectivity, warrant its security...

In the work Class norms for ESO (Compulsory Secondary Education) we produce a classification of class norms (of movement, of talking, of group formation, of initiation …); we analyse different processes to establish them ; we consider different possibilities to work with pupils and, above all we set forward the dilemma of action in the infringement situations. Even if we have been working on the educational sense and the coexistence of a norm, it starts being felt as a norm on the very moment that someone infringes it: at that point « something must happen », so that, both, those who have infriged it, and the rest of the group can check that it was an unacceptable behaviour. At that level, a dilemma appears : what can we do ? the action of teachers facing a situation of class norm infringement admits different possibilities (going from ignoring the transgression to imposing a serious punishment); they can all be valid. The key to professional progress consists in choosing adequately depending on personal aspects and on the situations that coincide in each case.