The first writing I did was producing worksheets and teachers' notes, which turned into a booklet for my own school.
In 1992 I was seconded to the Bath 5-16 project, published by Macmillan, at Bath University, and it was a real luxury to have time to write.
I also taught half the week, which was really useful because it helped me to keep my feet on the ground. It's very easy to lose touch with who you are writing for, and I think that's a problem with a lot of textbooks.
My husband and I later wrote a GCSE science revision guide. My son, who was doing his GCSEs at the time, insisted that every question in the book should also have an answerin the book - which many guides do not, and which we wouldn't have thought of otherwise.
Writing Go for Science for lower-attaining pupils has been exciting because we were starting at the bottom and working up - instead of what most books do, which is starting at the top and then watering it down.
We've tried to link science with the everyday, to make it more interesting and relevant. We've also given teachers tips on organisation, and questions to ask as they go round the class; it's so easy in science just to say to children "the beakers are over there" and never really talk to them.
You don't write textbooks for the money and you could certainly never retire on theproceeds . But you can always think of ways to improve what you're doing. Science textbooks are always in a state of flux because of changes in the curriculum.
At the moment there seems to be a lot of "quick fix" stuff around, slimmed down, minimalist guides (not like ours!), geared only to passing exams. These do have a place, but I worry they could take over from fuller, broader science books. The art of reading needs reinstating - and the idea that you can look things up in more than one book.
Being on the Standards Task Force is a constant reminder to me of the need to keep helping. It's also given me a greater awareness and broader feeling of who I'm writing for: you can't just think you're writing for your own pupils.
Janet Major was talking to Diana Hinds