In this paper we examine how agency is characterised by teachers and students when personalised learning is enacted in the contemporary open classroom. A case study is outlined that identifies teacher reasoning for practice, the use of physical and virtual learning spaces, and student reaction to teacher facilitation of personalised learning. Agency is conceptualized as a multi-faceted set of behavioural, affective and cognitive choices, as realised by both teachers and students, drawing upon the action possibilities of contemporary educational contexts. A model of the mutuality of teacher and student agency is outlined. The model shows how a shared understanding of the affordances of flexible learning spaces and personalised learning interact to both produce teacher and student expectations and perceptions of their own and other's choices and actions. Specific student choices and actions are examined in relation to problem-solving and open access of resources to achieve the task requirements. Implications are noted for teaching and learning in modern school contexts.