Jonathan Osborne on how teachers bridge the gap between pupils' knowledge and the world of science
How do you explain scientific ideas? This is the science teacher's daily task, but it is poorly understood. Everyone can distinguish a good from a poor explanation, but what is it that makes the difference? This book uses the findings of two years' classroom research to attempt one of the first detailed answers to the question. It is a seminal contribution to our understanding of a neglected topic.
To answer their question, the authors recorded many examples of the explanations offered by science teachers everyday in four secondary schools, two in the inner city, one in the outer suburb and a City Technology College. They then attempted to deconstruct the discourse and explore its function.
A rich picture emerged of science teachers telling stories - stories that bring into existence the many items that inhabit the scientist's world such as energy, mammals, fluids, density, amplitude, evaporation, newton-metres, mass, volume, and electrons.
Using a lucid and engaging style, the authors show how science teachers have an ability to create a gap between their pupils' understanding and their own world view. This arouses curiosity and drives the need to know - to close the gap and help students construct new meanings. For example, a teacher tells the story about Alexis St Martin, the French-Canadian fur trapper who had a gunshot wound in the side of his stomach. His doctor hung pieces of boiled egg through the hole to see whether or not they would be digested.
The story highlights the difference between thinking of eating as an everyday experience and thinking of it as a biological process. Eating is no longer a simply a means of gratifying basic desires but a complex story about proteins, carbohydrates and fats which are processed by stomachs, duodenums, small intestines, large intestines and so on.
This new understanding is brought about by a process which the authors call "didactic transposition". In the UK, unlike the rest of Europe, there is a tendency to associate the term didactic with an authoritarian teaching style and a lot of chalk and talk. However, here the authors use it to describe the way teachers turn scientific know-ledge into a form which is appropriate for teaching.
For example, an invisible sound wave is turned into something tangible and visible with the aid of an oscilloscope. There are many other carefully chosen examples which show how teachers selectively rework the established science, using a mix of stories, analogy, metaphor and demonstrations to help students construct an understanding of the scientific world.
This is an important book which helps us to understand what science teachers are doing as we explain the natural world to our students. Only when the process is understood can we move forward and improve.
It marks a welcome return to focusing research on the teacher rather than the learner. Explaining Science in the Classroom is essential reading for anyone with an interest in science education.