Recent migration combined with strategies to diversify the teacher workforce has led to complexities in teacher diversity identified by the term 'superdiversity' (Vertovec, 2006). This article builds on recent work on the processes of convergence and superdiversity (Wessendorf, 2011) by focusing on meaningful encounters in the mathematics classroom. A sociolinguistics approach is used to discuss the performance of teacher identity, focusing on accent. An analysis of power shows tensions between Standard English and local vernaculars, involving microaggressions and opportunities for intercultural learning. The article concludes by discussing coping with microaggressions and the systemic implications for school policies and initial teacher training. It shows how microaggressions offer opportunities for intercultural learning and how classroom spaces can be developed that promote both this and the dispositions of an intercultural habitus.