International audienceConsidering sociological features of teaching general topics in vocational schools, we make assumptions about conditions that allow students to engage in lasting mathematics activities. We design two situations and analyze the activity of students in theses situations, considering their involvement in the task and the mathematical nature of their activity. We then identify didactical conditions for a mathematical activity in vocational schools.Prenant appui sur des travaux sociologiques qui identifient des particularités de l'enseignement des disciplines générales en LP, nous faisons des hypothèses sur les conditions permettant aux élèves de LP de se mettre durablement au travail pour générer des apprentissages mathéma...