Science: UNDER THE MICROSCOPE

LEWIS WOLPERT ASKS: IS IT WHAT WE TEACH, OR HOW WE TEACH IT, THAT MATTERS?

ALTHOUGH I have taught for many years, I still find the process mysterious, and certainly regard myself as a failure when it comes to teaching university students. I have tried all sorts of methods but have come to the gloomy conclusion that my impact is minimal. I've also reached the conviction that so-called good teaching is bad for many students (the gifted are in a class of their own). It is rather like the Chinese Meal Syndrome - you feel fine at the time but are hungry again soon afterwards. A "good" lecture can give you the feeling that you've understood a topic, but the understanding soon disappears if you haven't had to struggle quite hard with it; for most of us, learning requires considerable effort. I was always impressed by the study which showed that the higher students rated their maths teacher, the worse they did in the exams.

I am, however, looking into some new methods that I will try out next year. There are exciting developments in the teaching of science to school children. A group at King's College, London, has developed a cognitive acceleration programme to encourage pupils' general ability to think. It is based on the idea that cognitive development (of the kind Piaget investigated) can be speeded up. Science teachers give special lessons during the first two years of secondary school, with activities that aim to bring about long-term effects: an understanding of variables and relationships; problems- solving that induces cognitive conflict; the ability to think about one's own thinking (known as metacognition); and the application of all these skills to other areas.

There are activities that concentrate on the key idea of the relationship between variables. In one example, the students (typically 11-year-olds) are shown a collection of shapes of different colours and sizes and work out which of these variables go together. In another, they recognise that the number of sausages goes up as their size goes down. There are also situations where there is in fact no relationship between, for example, the colour of a jar and its weight. Working through exercises like these gives the children confidence in using a fairly technical vocabulary.

Cognitive conflict requires them to think in a new direction. In one situation, they have a set of jars of different weights but similar sizes, and another set which have the same weight but get successively smaller. They record each jar's weight and then see if it floats or sinks when placed in water. They find that with only two variables, heavy things sink while light things float. Cognitive conflict occurs when they are given a jar which is the same size as a floater and the same weight as a floater but it sinks. They have to come to terms with the concept of weight for a certain size - ie density. In another, they have to find some way of extrapolating when the graph paper will run out. The students are encouraged to think about their own thinking and to discuss what they found difficult and how they came to solve it. They might, for example, begin to recognise a problem as involving proportionality of variables.

The extension of these experiences to contexts outside science teaching is also regarded as important. The children are introduced to the notion of probability by testing each others' ability to distinguish Coca-Cola from Pepsi. How many times must they get it right before they can be sure it was not just chance that got a classmate to the answer? Initially, they think that five times is a reasonable number. Then they spin coins and see how often five heads can come up.

Is all this effort worthwhile? Unquestionably, yes. The effect on over 4,500 students from more than 15 schools has now been analysed and the results are remarkable.There was an increase of nearly 20 per cent in grades A to C in GCSE results for science, and a similar (albeit slightly lower) increase in the grades for English. It is the latter that is particularly encouraging; it shows that clear thinking and thinking about thinking must be a central aim of education.