In the science classroom, there are some ideas that are as difficult for young students to grasp as they are for teachers to explain. Forces, electricity, light, and basic astronomy are all examples of conceptual domains that come into this category. How should a teacher teach them? The authors of this monograph reject the traditional separation of subject and pedagogic knowledge. They believe that to develop effective teaching for meaningful learning in science, we must identify how teachers themselves interpret difficult ideas in science and, in particular, what supports their own...