Spanning parent-communication and administration to content delivery and student monitoring, platforms have become an integral part of contemporary schooling. Building on two ethnographic episodes occurring in a Danish primary school in January 2020, this article engages in an analysis and discussion of how the ongoing "platformization" of schools affects the day-to-day relations of teachers and students in a 2nd and 9th grade class. The article draws on a posthuman theoretical framework to give an account of how two common education platforms used in the Danish primary school system -- the "MathFessor" platform for mathematics, and the "Gyldendal" portal for Danish language lessons -- become problematically constitutive of what and who matters in classroom interactions. By emphasizing and theorizing the relational embeddedness of education platforms, the episodes serve as invitations for a greater attentiveness to what bodies in schools can and cannot do in classroom-based platform practices. An attentiveness which, it is argued, extends well beyond the instrumental discourses of personalization, innovation, and efficiency surrounding the implementation and use of platforms in schools.