In Switzerland, as elsewhere, issues dealing with cultural diversity raise major challenges in education. At present, little is known about how students make sense of these highly sensitive societal issues and relate them to their everyday experience. Drawing on a sociocultural and dialogical approach to learning, this study aimed at understanding how the students made sense of themes related to cultural diversity. More generally, it sought to examine whether secondarisation (i.e. a transformation of everyday experience into a more generic and scientific form) took place. In this study, ten focus groups were carried out: five in primary school (11- to 12-year-old students) and five in lower secondary school (13- to 14-year-old students) in the French-speaking part of Switzerland. The specificity of the research design consisted of setting up a situation that had both similarities and differences with lessons on cultural diversity that had previously been taught in the classroom. We assumed that this would create dialogical tensions and thereby shed light on the obstacles that may arise when themes related to cultural diversity are taught in school. Analysis of the discursive dynamics of the focus-group discussions showed that education for cultural diversity cannot be considered independently of the student's other spheres of experiences. Personal, social and moral dimensions are part of the students' effort to make sense of the themes under discussion. Talking about cultural diversity, even though with pleasure and involvement, cannot be equated with learning and transforming these themes into scientific concepts. Moreover, dialogical tensions can create unexpected effects and even bring about the very phenomena that education for cultural diversity is supposed to fight.