The importance of school buildings is rooted in the vitality of education for societal development. Literature perceives learning as a social process, enriched by student interactions and self-directed activities, and the school design should afford those learning practices. The term afford refers to spatial affordances which are defined, in this paper, as the set of possibilities for activities offered by the spatial design to students. Therefore, research on school buildings requires a broad investigation of the spatial design, to uncover the design potentiality and explore the actuality of school operation, in terms of the occurring student interactions and self-directed activities (as representations of social learning). This investigation outlines the research scope, while more attention is drawn towards informal learning spaces outside classrooms, including corridors, open-plan studios and social spaces. This paper focuses on the affordances of the spatial design of secondary school buildings. It presents the outcome of quantitative spatial analysis (using Space Syntax tools) on eleven UK schools, designed by three architecture firms, supported by qualitative interviews with the architects of those schools. This data set explores the school design potentiality for possible learning practices. The paper, thereafter, presents quantitative recording of student interactions and self-directed activities in two of the eleven schools, supported by qualitative interviews with the school managements and teachers; and student questionnaires. This data set explains the actuality of student interactions and self-directed activities, relative to operational managerial schemes and student preferences. Findings discuss the influence of functionalities allocation and configurational accessibility on student interactions, activity types and distribution. This is portrayed through the example of school corridors which afford interactive learning if being highly accessible and connected to open learning spaces. Nevertheless, operational managerial schemes and student preferences still influence the occurring activities. The research outcome explains the school actual operations, and how they correspond to (or divert from) the original design potentiality. This outcome contributes to the existing knowledge on the student social life in schools, and how the spatial design and school rules impact activity types across informal spaces. This possibly links to futur e work on interactive design processes that include architects, teachers and school managements to reduce the gap between school design intentions and operation.