There are education agencies out there that produce resources for schools by businesses/charities etc. I used to work for one and now work freelance contracting teachers to do writing for client programmes when required.
Check out www.edcoms.com, www.hopscotchconsulting.co.uk, http://www.nationalschoolspartnership.com/
Thanks for that, I'm planning on continuing with my tutoring and exam marking and eventually running a tutoring centre. I think this would be a nice sideline and quite complementary with my other lines of work. I'm writing my second resource for zigzag now, so I'll build up a few more and them maybe send my CV off to other publishers.
Big publishers use a lot of freelancers / authors to write resources, so there is work out there. The fact you have had some work published is a plus, so you already have an established portfolio.
You'd really need to identify names of the publishers/editors working in your subject/level specialism and approach them. Or also look for contacts such as a web content manager who may well have a need to supply lots of content for websites etc.
Things such as textbooks are usually written by very established authors - and with the big publishers they normally know what they need written, then author teams provide the material (rather than writing a book and 'pitching' it to them IYSWIM). Untested authors would probably be used for providing supplementary material, such as photocopiables for the back of Teacher's Books etc.
I don't know what the going rate is - but I'm not sure that in itself it's particularly lucrative - the people I know tend to combine it with teaching or other work (and there is possibly an advantage in being a practising teacher and testing your material out in the classroom).
PM me if you want any more info. I'm not in a position to help directly but do have some experience of this area.
I've just had my first resource approved for zigzag education and it is going through the publishing process now. I am a former teacher, but I loved writing so much that I feel that I have found my niche. I'm writing more resources for zigzag - but I was wondering if anyone had any advice on establishing a career in this area. I was looking at the websites for other educational publishers, like Nelson Thornes and Pearson - but I'm not sure how I'd go about getting work as a writer with them. Does anyone know anything about this area?