This article examines multicultural classrooms through the selective permeability model, which posits that individuals encounter different action possibilities or affordances in the same setting. The goal is to illuminate how educational environments may support some students while disadvantaging others, thereby causing situated cognitive harm. The article proceeds in several parts. First, it explores selective permeability in relation to what Gibson describes as “positive” and “negative” affordances, articulating how these polarities can change depending on a person’s cultural background. Second, it integrates (...) insights from cultural psychology, such as the influence of regional geography and city design on behavior-constraining cultural norms. These norms can productively funnel actions and learning. Yet when a student’s cultural norms clash with tacit classroom prescriptions, the situation can be analogous to arriving at a rink with rollerblades only to be placed on ice: the learner confronts action limiting negative affordances and undergoes situated cognitive harm. Third, the article presents qualitative and quantitative data that clarify how culture moderates what students find helpful or hindering. Notably, incongruent norms are not always detrimental; under certain circumstances, they can serve as a catalyst for growth. (shrink)