A long time ago, in a country not far away, when the world was young, science education was divided into three parts. They were called biology, chemistry and physics. Each was beautiful in its own individual way, and attracted many admirers. Although it was sometimes difficult to tell where one part started and the other left off, most people were quite happy with the arrangement. The tripartite division of science was regarded as a good thing. However, like many good things, it couldn’t last forever Let me tell you about my own first love - chemistry. All that glassware, the fun to be had with a live flame, the ever-present risk of the experiment going excitingly wrong, the gases that popped, the acids which fizzed, the colours which changed when solutions were mixed: - it was magic, pure magic.

Then I went to school and realised that my chemistry set was a pale imitation of the real thing. There was much more to chemistry than I had dreamt of. There were symbols to be learned, equations to be balanced, molarities to be calculated. I discovered the world of wet chemistry, of burettes with their glass balls in rubber tubes. I learned how to spell phenolphthalein correctly and potassium incorrectly. I memorised the early parts of the periodic table and rejoiced in the patterns therein. Most of all, I enjoyed the uniform. Chemistry and physical education were the only two subjects which allowed their students to indulge in fancy dress.

Then, one day, my infatuation with chemistry was over. It wasn’t her fault that I jilted her for physics. The fault lay with a matchmaker called maths. I found it really easy to hang out with maths. You could always tell where you were with her; you were either right or wrong. There was no messing about with excuses for the unpredictable, everything could be explained and understood in clear logical terms. And yet, I found maths to be cold and unromantic. There was no spark between us. Love needs a bit of risk, some sense of more to come I and so I turned to physics. The rest of the story is private.

Then, about 20 years ago, I relinquished research and became a teacher. A teacher of physics. I taught physics not only because I could do it, but also because I thought it was important that others should also love physics. She had been good to me over the years, helping me to acquire a set of mental skills and attitudes which largely explained the sort of person I had become. I wanted more people to be like me. So I became a teacher.

I worked in a large comprehensive school (Cedars Upper School) with a team of people known as the science department. Some of them taught physics. Others taught chemistry. The rest taught biology. Each of them loved their subject and couldn’t understand why anyone would want to teach anything else. Although we had a lot of fun at each other’s expense, we worked happily together. Our students were successful in their exams and many of them flirted with our subjects at A-level.

We didn’t do any research. We didn’t advance the frontiers of science. We had chosen the less prestigious path of providing, through education, a population which might appreciate what science could do and be happy to continue supporting the enterprise. Many of us were of the Woodstock generation.

I prospered. Eventually, I became top teacher in the science department at Cedars. Shortly afterwards, the national curriculum and key stages arrived on the scene. It was the best of times, it was the worst of times. The best part was that, from henceforth, all students would study science to GCSE. The worst part was that the thought police at the Department of Education dissolved the boundaries between physics, chemistry and biology to create dual award science.

It is an interesting creation. From the outside, dual award science presents a unity, with the unique privilege of being worth twice as much as any other GCSE qualification (and four times as much as some). From the inside, it looks like biology, chemistry and physics crammed side by side, with earth science jammed into chemistry. Altogether, it is an interesting compromise which matches the requirement of science-education-for-all with science-education-for-future-scientists, as well as recognising that a well-balanced education involves maths, English and a range of other subjects chosen by the students.

Dual award didn’t just appear overnight. In the years before the arrival of the national curriculum, key stage 4 and attainment targets, a double-award GCSE had evolved to fit the needs of students who couldn’t decide which of the three sciences to drop at the age of 13.

Dual award GCSE was popular at Cedars. For some years it competed successfully with physics, chemistry and biology. Our main problem was staffing it. Since it occupied two blocks on the timetable, dual award GCSE had to be delivered by two teachers. Each teacher would have to teach at least two different sciences, if not three. Most of us were not up to it, so dual award was taught by the sprightly few.

The main problem with dual award science is arranging for effective teaching. At Cedars, each group is taught physics, chemistry and biology separately, in specialist labs, usually by a specialist teacher. This recognises the fact that many of the staff, particularly those who teach at A-level, are most efficiently deployed in teaching their specialist subject. They spend less time preparing, leaving more time for marking and delivering. But most of all, their enthusiasm for their subject can only encourage their students.

My main concern about dual award GCSE science is not what it does for the students, but what it does for potential recruits. I can just about remember a time when it was easy to find replacements for physics and chemistry teachers. Since the arrival of the national curriculum, the supply of able and enthusiastic young physics teachers appears to have dried up.

Perhaps they are frightened by the idea that they may have to deliver more than one science. Perhaps the parcelling together of three separate sciences into a single dual award package has been instrumental in discouraging young people from becoming science teachers.

Michael Brimicombe is head of science at Cedars Upper School, Leighton Buzzard, Bedfordshire, and a principal examiner for GCSE science and physics A-level