Music is deeply entangled with human activity and can play various roles in our lives, also in the lives of children. A large part of children's day-to-day life in Norway takes place within a school context. However, research on children's musical lives within a primary school context is scarce, and there is little knowledge of how pupils engage and interact with music throughout their school day. Building on classroom observations of 4th graders in a Norwegian primary school, this article addresses the intra-actions of pupil(s) and music(s) at school from a posthuman and new materialist perspective. Through a diffractive reading of data and a 'thinking with theory' approach, we investigate how pupils and music intra-act within material-discursive school practices. Our results show that the intra-actions of music(s) and pupil(s) are connected to the norms and rules regulating the classroom and that these understandings have material effects.