International audience The paper focuses on the determinants that impact teacher's didactic activity in class. These determinants are the result of interaction between internal and external processes that have effects on teacher practices and the differences between those practices may create inequalitie. The relationships between context and situation are examined using didactical and sociological approaches. In this perspective, the context is no longer considered as a notion that ''likely imposes, conditions, configures situations and thus determines actions (especially of a didactic order) to be carried out'' but rather, as a ''notion which would contribute to reflect on the situations and suggest interpretations'' (Castelloti, 2014). " Contextualization processes " are thus defined as ''the set of interactive relationships between the teacher and the context while practicing'' (Marcel, 2002). This definition allows us to ponder on the following: where does the context take place and what is the role of the actors during a teaching and learning sequence. In that line the contextualization work of the teacher, which means his competency to associate different scales of context (dispositional, subjective contextual and situational) consists of understanding and acting appropriately with regard to students' activities. The data come from a comparative study of two PE teachers teaching table tennis lessons in disadvantaged schools. Qualitative analyses of videotaped lessons and teacher's semi-directive interviews conducted through self-confrontation point out various forms of " professional gestures of contextualization " that are specific to each teacher. These contextualization competencies vary according to how much they are anchored with the culture, the implicit norms of the institution, and the professional history and experience of each teacher. Teaching in disadvantaged school requires teachers to adapt their actions