The scope of action within which teachers are assumed to engage in reflective, situated judgement and to be praxical is both multidimensional and is non-binary. It is multidimensional in that the range of ways in which teachers interact with their students covers aspects including the development of understandings and abilities in content areas of the curriculum, being aware of the students’ needs, emotional, physical, psychological and social, and in ways that relate to the general moral development of their charges. It is non-binary in that within any dimension of their work, the scope for exercising situated judgement is not absolute, but is modulated by the degree of prescription and regulation to which it is subjected. The project, informed by the practice architectures of Kemmis and Grootenboer (2008), and by Weick’s (1976) organizational couplings, takes as cases the curricular and pedagogical structures and constraints under which teachers of science in Sweden and of mathematics in Ontario, Canada conduct their practice.