Explaining Science in the Classroom

Many of us recall, nostalgically, the halcyon days of Nuffield Physics which emphasized direct learning through hands-on activities - `do and understand!'. And the role of the teacher changed. Discovery/individualized learning, worksheets, continuous assessment, modules, computers, videos, interactive systems, Internet.... And the role of the teacher became more and more stressful. Administration, assessment, preparation, discipline... new equipment, new techniques, new problems, new labours. It's good to talk This book shows in a compelling and convincing way how one of the central roles of a science teacher can be re-established by `bringing attention back to how teachers explain - back in effect to a neglected aspect of rhetoric in the science classroom'. It is concerned primarily with teachers talking to groups of students. And to demonstrate the efficacy of the spoken, or in this case the written, word the book contains no photographs, no charts, no graphs, no equations and only three relatively trivial diagrams. The authors consider teaching techniques involving attention-grabbing interactions between teachers and students. In a series of recorded science lessons teachers explain various science concepts and the authors then analyse the nature of these explanations. To start a lesson a teacher might provoke a disagreement. Leon: Do you think that you can tell, if you're having a baby, if you're having a boy or girl? Student 1: The shape of it, that's what I heard. Student 2: I don't believe that. Student 3: That's what I heard... Leon: Okay, a little baby brother, a penis about this big, okay.... True? You're telling me that that alters the swelling. Alternatively a teacher could use students' interest in, for example, bodily functions to start a discussion. Retelling stories, such as the bizarre episode of the French-Canadian fur trapper whose stomach was opened by a gunshot wound, and whose doctor used the opportunity to study the process of digestion, is another approach illustrated in the book. Interest can also be aroused by a startling demonstration such as dropping potassium into water. An unexpurgated account of the pupils' reactions then leads to a discussion of safety procedures. What of the physics examples? Alas they are few, far between and far from fun! Indeed we are told that `The question of what determines the period of oscillation of a pendulum, not to mention how to analyse motion under gravity, might stand as prototypes of the supremely uninteresting'. Can physics no longer compete with sex and violent reactions? Explanations Explanations can involve collecting and reshaping ideas from the class, offering a `story', giving the class new words to be practised or simply stating the theory and discussing applications of it. Scientific explanations are analogous to stories of how things come about, but the actors (`entities') in the story are often unfamiliar. These entities, material and abstract, must first be mastered. `Explanations are like the tips of icebergs with a large amount of supporting knowledge lurking below the surface'. Before knowledge which is appropriate to a scientific community can be used in schools it has to be `reworked', that is adapted to teaching at a given level. Finally the scientific theories must be shown to relate to the real world of matter. `The student certainly learns science in interaction with a teacher, but the student also constructs explanations in interactions with the physical world. We might label this `material semosis'. This looks surprisingly like hands-on experience! So have we come full circle... and reinvented the wheel? Explaining as communication This is a book about communication. It is copiously illustrated with transcripts taken from recordings of secondary school science teachers explaining science concepts. It is a pity that the commendable communicating skills of these teachers have not always been matched by the clarity of the authors' analyses. Here is a paragraph from `Explaining as Communication'. `We therefore see the unity of explanation not as deriving from the form of texts or of units of texts, but from patterns of factors which influence explanatory contexts. The textual units which express or realize explanations are quite diverse. Their diversity is to be accounted for in terms of the social and institutional structures of explanatory contexts. Thus we have not arrived at a taxonomy of explanatory forms; but instead developed a means of describing characteristics of explantory contexts'. Follow that!?