This paper focuses on a range of examples from UK sixth form educational contexts to explore the role of space, knowledge and power in the gendered constitution of material bodies in classrooms. Drawing on Karen Barad’s (2007) theorizations of cuts, phenomena, apparatus and intra-action, it analyzes the ‘small but consequential differences’ which, Barad (2007, p29) argues, constitute the practices that matter in the differential production of persons, interactions and social contexts. In aiming to give ‘matter its due as an active participant in the world’s becoming’ (Barad, 2007, p136) the paper seeks to: • Cast an analytical gaze on how power and knowledge production works with and through the boundary-making practices of inclusions and exclusions; • Identify the ways in which spatial ‘cuts’ are instantiated through dynamic becomings in specific gendered educational practices; and • Think through some of the ethical implications of Barad’s notions of epistemological-ontological inseparability, intra-action and entanglement. The paper is grounded in Barad’s notion of bodies as material phenomena and space as a material-discursive apparatus of mattering. It adopts a diffractive approach, in which insights are ‘read through’ one another to analyse the ‘situated accomplishments’ (Francis, 2008) which constitute the space-gender-power-knowledge nexus in post-16 classrooms.