When teachers at Thomas Telford city technology college write materials for the school's money-spinning online publishing arm, they know there's something in it for them.
The Shropshire school pays them a small fee for their work, and although they have to give up the right to re-sell it to other publishers, no one seems to be complaining.
"We are not only getting paid for doing a bit of extra work, but we can also use the stuff we have written with the children in this school to the benefit of our own teaching," says head of maths David Berry.
He and five members of his team have created an online GCSE maths course, partly in their own time but using equipment provided by the school. The course is sold to other schools at pound;600 a time, with the profits going into a trust that is helping to finance educational initiatives such as a new city academy in Walsall. Mr Berry will not reveal how much money he has made from his contribution to this venture. But he stresses that teachers who choose to get involved in the school's publishing activities benefit professionally as well as financially.
"If you are writing online materials for children you will maybe never meet, it certainly challenges you and makes you think about your own teaching methods," he says.
The teachers who write these materials all understand the rules, he adds. They know that their work will go through a quality assurance process and that they will be paid only after it has been approved and they have agreed to transfer their copyright to the school. In other schools, the position on teachers' intellectual properly is less clear cut. Traditionally, teachers who have turned worksheets or lesson plans into textbooks have been able to strike deals with publishers and earn royalties from their work. Some have even managed to make personal fortunes. But the technical resources needed to develop software materials and their huge commercial potential mean that this laissez faire approach is probably on its way out.
The law says that if someone writes books, articles or other materials in the course of their employment, the copyright belongs to the employer, unless the contract of employment says otherwise. But for teachers, the pay and conditions document says nothing about intellectual property rights, and their position during "the course of their employment" is unclear. Are they hired just to teach or also to produce teaching and learning materials?
"The contract is an open-ended one in terms of work commitment," says Graham Clayton, solicitor for the National Union of Teachers. "Our advice to members is that if they wish to retain copyright over work that they produce, they should make it absolutely clear that they are doing it at home, that it's not part of any school work and that they are not using working time to produce it."
But as Mr Clayton points out, there is some overlap between work that is produced at home and at school. Even worksheets or software that are not specifically intended for use in a teacher's own school will draw on areas of knowledge and skills acquired at that school.
Alan Stevens, head of Sawtry community college in Cambridgeshire, is in no doubt that producing online materials is a contractual obligation for teachers.
"Teachers' traditional way of working was to create notes and worksheets and what we've asked them to do is transfer those ways of working online," he says.
Sawtry college has bucked the trend represented by schools such as Kingshurst city technology college in Birmingham and Thomas Telford, which has made millions from selling teaching materials. Instead, the community college has put coursework on a website which anyone can access free of charge.
"We may not gain financially, but we will gain in many other ways - in the general ethos of the school, in the reputation of the school and in the calibre of staff we may attract in the future," says Laranya Caslin, the school's website designer.
With no money changing hands, intellectual property rights are unlikely to become a bone of contention at Sawtry. But if a school takes a more commercial approach, it needs to ensure that the teachers who create software or other teaching materials know where they stand.
Dixons city technology college in Bradford did just that when it recently launched Interactive Learning, a company that produces education software and is a wholly owned subsidiary of the school. Dixons seconded a teacher to the company, making it clear in his contract that the school owns the intellectual property rights to the materials he produces. In the higher education sector, a working group on property rights has suggested that staff contracts should be changed so that lecturers joining a university or college automatically assign the copyright on any software or teaching packages they create to that institution.
A similar solution in schools would not go down well with teachers who supplement their income with royalties from textbooks or software products. But it would at least remove the uncertainty that currently surrounds the question of who has the right to profit from teachers' ideas and creativity.