This article seeks to examine the neglected sociomateriality of the classroom and investigates how space, matter and human actors are entangled, interact and take part in the 'space-producing action'. Rather than approaching the classroom as an objective collection of physical units or a stable grid, we see it as something alive, a performance which can only be understood from inside the classroom. To gain insight into the ongoing constitution of the classroom, we have written classroom biographies together with nine primary school teachers. A first analysis of these rich biographies reveals the permanent interplay of human and non-human actors and their multidimensional relationships, from a new teaching aid urging the teacher to resort to traditional classroom organisation, to the rearrangement of classroom furniture in order to implement a new working method, to the manufacturing of seats from washing powder barrels. All of this reveals the classroom as a 'potential space' -- inviting teachers to become an active part in its spatial constitution and thus allowing classroom ownership.