"This is an impressive book. It is an example of that rare item - a book about complex scientific ideas, expressed in clear, simple language - built on real teacher - learner conversations. Starting in the classroom, or the laboratory, with the most common occurence - a teacher offering an explanation, it proceeds by analysing the nature of specific explanations so that teachers can gain fuller insights into what is happening. Having teased out the processes of explanation, the authors then reconstruct them showing how elaboration, transformation and demonstration can enhance the understanding of the learner." Professor Peter Mortimore * How do science teachers explain science to students? * What makes explanations work? Is explaining science just an art, or can it be described, taught and learned? That is the question posed by this book. From extensive classroom observations, the authors give vivid descriptions of how teachers explain science to students, and provide their account with a sound theoretical basis. Attention is given to the ways in which needs for explanation are generated, how the strange new entities of science - from genes to electrons - are created through talk and action, how knowledge is transformed to become explainable, and how demonstrations .