Throw the monkey into the sea...
Throwing a monkey with a ball and chain around its leg into the sea and asking how it escapes is far from the conventional idea of what chemistry is all about.
But such an experiment is a model of heurism - an approach to science based on pupils' own enquiries, And this is the key to the way chemistry should be taught, according to Glyn James.
James has this week been honoured with the annual Salters prize for his life's work in the field of chemistry. He has spent his entire career teaching the subject at Christ's Hospital, an independent school founded by Edward VI in 1553 for bright pupils from poor families.
"When I was at university a huge body of knowledge was thrown at us. But we also had mechanistic lectures to demonstrate how and why chemical reactions took place," says James. "I thought: 'If you can do this at university, why can't you do it at school?'" Christ's Hospital, in Horsham, West Sussex, has a tradition of heuristic approaches. In fact, the enquiry method of teaching science was pioneered at the school at the turn of the century by Professor Henry Armstrong, a leading figure in chemical education. Armstrong's story of the (wholly fictional) monkey encourages pupils to examine the properties of salt water, and the extent to which, being denser than water from a tap, it can prevent an object from sinking.
"A science teacher should be seen by his students as a co-inquirer, not an authority," says James. "He should always answer a question with a question. "
The second edition of the Nuffield chemistry A-level course book, which James helped to write in 1984, was born out of this idea, and all his lessons are based on it. When starting a topic, he tries to give it a context and encourages students to think as widely as possible about the subject.
James asks a lot of questions during the lesson to get their minds in gear: "How does a monosaccharide become a disaccharide? What happens when glucose and fructose come together?
When he retires at the end of this year, his pupils, who like all others at the school wear a curious uniform of black knickerbockers, long navy coats and bright yellow knee socks, will hold on to the enthusiasm he imparts.
They have no hesitation when it comes to recommending him or his teaching methods, which have enthralled many of them for four years.
"We start off our lesson talking about what might happen with our experiments, then we test it. Once we've finished we talk about what actually happened, " says 17-year-old Ben Cook. "We do lots of practical work, which means we're more likely to remember what we've learnt. We are encouraged to try out experiments which are not necessarily part of the A-level course. We even made margarine once."
James believes there are two important factors that should be involved in teaching chemistry. Students must understand what they are learning and realise the importance of their experiments.
"Organic chemistry is about making useful compounds for mankind, like dyes and drugs. Pupils need to see how it works," he says. "Teaching pupils to make aspirin and paracetamol can capture their imagination."
This is why experiments are a vital part of James's lessons. He is keen to get down to the practical. "I'd like you to do a Benedict's test on glucose, fructose and sucrose," he tells his students. "You may be in for some surprises here. Let me know what you find."
Students cannot help but find themselves fascinated. Oliver Derbyshire, 17, says that he always wanted to be an architect until he came to James's lessons. Now he is applying to Oxford to study chemistry.
Another student, Edward Husband, says: "Our learning is very visual and interactive and the experimental work helps you to take the subject in. "
James says he uses experiments to improve pupils' understanding. "You have to look at whether the priority is knowledge or the understanding that lies behind it. I want my students to go to university with understanding."
All too soon, the chemistry lesson is over and the Bunsen burners are put away. The pupils don their navy coats and the school band, complete with drums and trumpets, marches them into lunch, as it does every day.