Teachers who are themselves insecure in their knowledge of science can find the uncomplicated transmission of knowledge attractive (Osborne and Freyberg, 1985). Transmissive teaching avoids discussion (since learners lack knowledge worthy of consideration) and interactions which might reveal teachers' uncertain knowledge and so alter power relationships in their classrooms. The view of science as a body of unambiguous right answers for transmission into learners' heads can then trap teachers into a teaching style inimical to their own and their students' learning, or into avoidance of the subject entirely.