Teaching, like other professions, involves the performance of contingent functions. This suggests three basic questions: What do teachers do? What affects what they do? How do they do it? Together, these questions provide a three-dimensional framework which can be used to plan, analyse and evaluate teaching. Such a framework falls short of a prescriptive theory but can inform the judgements that teachers and students make. It also offers one way of conceptualising teaching as a unitary discipline.