This paper is based on findings from a three year collaborative action research project on classroom teaching and learning. The research, which involved 33 teachers, over two thousand students from six schools, and the authors, centred on exploring how various features of the classroom context influence teaching and learning processes. We interpret project findings as indicating the importance of balance between cognition and affect for effective teaching and learning. We advance the notion of challenge as a way of conceptualising this balance. Challenge comprises a cognitive/metacognitive demand component and an affective interest component. Nine major features of a teaching/learning event were found to interact to influence these cognitive and affective components of challenge.