A major trend in science, mathematics and technology education (SMTE) is the broadening of the curriculum framework beyond the subjects to incorporate social dimensions and the interests brought by the student to learning these subjects. At the same time as curricula are changing, the challenges to teachers are increasing. New approaches in SMTE lead us to look at how teachers and students are responding. Listening to them, it becomes apparent that the nature of the subject taught and learned provides a familiar home for the work they do together, but topics and classroom practices are becoming markedly different from the usual focus of the teacher's subject expertise and student induction into pedagogical rituals. This paper discusses the implications of these reform efforts in relation to the didactical and pedagogical challenges which flow from them. We go on to consider how, in practice, these changes bear on the concept of teacher professionalism.