A new exhibition at the Victoria & Albert museum shows that children make some of the most inspiring, imaginative and brutally honest clients.

These clients are a tough bunch to please. If they don’t like an idea, they shout “that’s rubbish”. They fall asleep when a presentation takes too long. They like colour overdoses and use The Simpsons as a decor reference. Oh, and they have almost no money.

Yet despite all these drawbacks, children have become the must-have clients for big-name architects, as the joinedupdesignforschools exhibition that opened this week at the Victoria & Albert museum reveals.

Fifty-three practices have taken part in the projects, including Terry Farrell and Partners, Richard Rogers Partnership and Alsop Architects, as well as up-and-coming firms such as Urban Salon and Walters & Cohen. They worked on creating spaces for children over the course of a school year, for the rather modest fee of £10,000. Clearly, the thought that there is no point in creating beautiful buildings for children to vandalise is on its way out. Rather, the prevailing idea is that involving children in design is rewarding for all parties.

The Sorrell Foundation was founded in 1999 by John Sorrell, now chairman of CABE, and his wife Frances with the aim of “inspiring creativity in young people and improving quality of life with good design”. They did not have any money to begin with, so they relied on their friends to provide their time gratis. Now their foundation receives £2m from the Department for Education and Skills and its activities feed into initiatives such as the government’s Building Schools for the Future programme.

The joinedupdesignforschools project involved improving school spaces from the study room to the playground, dinner room and toilets. In the past five years, 10,000 pupils – aged four to 18 – in more than 60 schools across the country have benefitted from the programme. Ten of the projects, ranging from in cost from £15,000 to £480,000, have been implemented and a further 10 are about to receive funding. The DfES and the schools themselves finance up to half the schemes; the Sorrell Foundation negotiates with local education authorities to raise the balance. So far, the foundation says that the responses from the LEAs have been “encouraging”.

But what do schools dreamed up by the children look like? The V&A exhibition reveals common concerns and aspirations. Pupils want a colourful, safe environment conducive to study and communication. They also want buildings they can be proud of. The results of the collaborations are amusing and surprising.

For instance, the pupils of Deptford Park Primary School in London, who worked with Mike Davies from RRP, turned their toilets into a Caribbean beach. Design consultancy Graven Images introduced a treehouse in the classroom of Quarry Brae Primary School in Glasgow.

Children show a real clarity of thinking. They are the most devastatingly honest clients you can have

Frances Sorrell, the Sorrell Foundation

Marks Barfield created a sheltered outdoor area for the Newquay Tretherras School with a Hollywood-style school sign. Both the Deptford and the Newquay projects will soon be a reality.

So did the clients behave themselves? Frances Sorrell says that the designers were all impressed by their young customers. “They show a real clarity of thinking. They are very pragmatic and don’t behave silly in any way. They are also the most devastatingly honest clients you can have.”

Not all projects turned into brick and mortar, but Sorrell doesn’t feel any frustration. The children have learned new skills, their ideas and opinions have been listened to and, at the end of the project, they own the designs.

The Sorrells’ idea is not the only initiative to introduce children to better design. In its first year, the Junior Open House programme, funded by the Heritage Lottery Fund, used London architecture as a learning tool for 11- to 14-year-olds from 23 London boroughs. The number of architects involving children in their consultation work for schools is rising, and architects and designers agree that working with children is a stimulating and fruitful experience.

So maybe the time has come to introduce architecture to the national curriculum?

Joinedupdesignforshools runs from 21 February to 18 March at the Victoria & Albert museum, South Kensington, London