Since 2010, French middle schools with a high enrolment of difficult students have benefited from a compensatory policy called "Écoles Collèges et Lycées pour l'Ambition, l'Innovation et la Réussite" (ECLAIR) (Primary and Secondary Schools for Ambition, Innovation and Success). These difficult students frequently misbehave, disengage from academic tasks and provoke conflict in the classroom. However, some physical education (PE) teachers are able to develop successful teaching strategies. This case study has analysed precisely the activity of the teacher in relation to the activity of the students in these difficult classes. It examined the successful forms of interaction between teachers and students in PE classes and sought to determine the meaning of these interactions in structuring a "difficult" classroom culture. The study was conducted within a situated cognitive anthropology framework in middle schools enrolled in the ECLAIR programme. Eight successful PE teachers and 24 students between the ages of 12 and 16 were involved in this qualitative study. The results revealed that, in spite of divergent intentions, the respective activities of the teachers and students remained coordinated. This coordination was based on a recurrent form of classroom interaction that made use of processes of ostentation and masking.