Introduction: Our study aims to analyze the enactive knowledge mobilized during teacher-student interactions in physical education lessons with difficult classes in vocational high school. These classes are considered "difficult" because they concentrate a large number of pupils who are referred to them because they have no choice. This lack of choice makes it difficult for these pupils to engage in school work and is the cause of deviant behavior and school dropout. Methods: This study was conducted within the methodological and theoretical research program of the course of action. We analyzed the individual activity of nine teachers and 18 students during a PE lesson by collecting audiovisual data and conducting self-confrontation interviews. These data were processed in several stages: transcription, identification, and typification of the components of the experience. Results: The results show mutual active knowledge between the teacher and the "difficult" students: emerging from the context, anchored in a dynamic of experience, coupled with the concerns of actors. The teacher classifies the profiles of students according to their reaction to authority and their difficulties, by spotting students' "thermometers" of the class climate. Some of the knowledge of students is coupled with their concerns to avoid boredom, to avoid trouble with the teacher, and to avoid trouble with their friends.