What would a dragon put in its shopping basket? Crisps, pizza, plenty of meat, say Year 1 children at Turnfurlong Infant School in Aylesbury. But most of all, a toothbrush and a prodigious amount of toothpaste.

An epidemic of dragons broke out in primary classrooms last year, thanks to the National Gallery’s choice of Uccello’s “St George and the Dragon” for its Take One Picture scheme. Home corners became dragon’s lairs; children produced wire dragons, poetic dragons, wooden dragons, animated dragons - some of them displayed at the National Gallery itself.

At Turnfurlong, the theme prompted dragon masks and shadow puppets, dragon symmetry, dragon science (what if George’s saddle was made of jelly?), and dragon geography (where would a dragon live in Aylesbury? Down by the canal of course).

This 300-pupil school embarked on the Take One Picture project like all schools do: by sending its staff on one of the National Gallery’s Creative Spaces training days. Introduced to Uccello’s 15th-century masterpiece, head Jan Tyson was initially sceptical: “When we first saw it we thought the colours were a bit dull. We were worried that it was a bit gory, because the dragon is all bloody where George has stabbed him: it seemed a bit gruesome for our children. We also thought we might get bored with one picture; that we might get dragonned out!”

But during last summer, the staff agreed to fit as much George and dragon as they could into existing plans - for example, adapting healthy eating lessons to include dragon as well as human nutrition (hence the shopping basket exercise). The school also appointed sculptor Kevin Harrison as its first artist-in-residence.

At the start of the autumn term, they gradually introduced the painting to the children (pound;5 per copy for each classroom), covering most of it up and asking them to explore closely the area they could see. It was at this point, says Jan Tyson, that the creative potential of the scheme became clear: “The children saw it in completely different ways. Teachers came back to me, saying ‘I would never have thought of that’.”

Without having been told the story of George and the dragon, which the school deliberately withheld at the time (though it became the subject of a parents’ and staff panto at the end of the summer term), some classes thought the princess was taking the dragon for a walk when a nasty man came up and hurt it; some that the princess was trying to rescue the dragon; some that the dragon was trying to rescue the princess. There were discussions about the significance of the clouds - divine intervention or another dragon? - about what might be inside the cave, what the picture would look like from the other side, why the dragon had an antenna (George’s lance) protruding from its forehead.

Turnfurlong’s teachers modelled their completely open attitude to the children’s suggestions on that of National Gallery staff, says Mrs Tyson:

“When we take the children there on a visit, no one ever says ‘That’s a ridiculous idea.’ By the end of a visit, even our shy children are hazarding ideas.”

Nevertheless, when it came to making their own dragon, the children were extremely prescriptive. It had to be green, and it had to have four legs (Uccello’s has two), they told Kevin Harrison, who spent 10 days in school, including one staff training day, teaching everyone hammering, sawing, drilling, sanding and clamping.

Even five-year-olds managed the new woodwork techniques without accident, says Mrs Tyson: “We had three banged thumbs in 10 days; that was all.”

Parents who came in over a weekend to help finish the wooden figures of George (in full army camouflage), princess, horse (a unicorn, at the children’s insistence) and the dragon, could barely be persuaded to let the children take their turn with the tools: “The school was buzzing. It was alive with all this work going on. There was so much sharing and helping each other; so much creativity and confidence.”

It is not unusual for picture-stimuli to produce enthusiasm and results that take everyone by surprise, says Ghislaine Kenyon, formerly the National Gallery’s deputy head of education: “We had a Kent school where the teacher asked the children to make their own dragons over half-term.

One boy was failing quite significantly in lots of areas of the curriculum.

He went home and came back with this wonderful dragon made of wire and metal which he had soldered.

“It turned out that his dad, who is not artistic, has a workshop and liked tinkering with cars. But the boy is very artistic and he gained huge recognition for having done this, in a way that he had never had before.”

Take One Picture has been going for 10 years. Each year, 3,500 primary teachers go on the National Gallery’s continuing professional development courses, and get the chance to join in the scheme, with a poster of the painting and a resource pack. A website was launched last year, with an archive of pictures chosen in previous years, including Holbein’s “The Ambassadors”, Constable’s “The Hay Wain” and Titian’s “Bacchus and Ariadne”. It contains examples of children’s work in response to pictures, and a bulletin board for teachers. Says Karen Hosack, the gallery’s new deputy head of education: “It’s the most popular scheme, with amazing creativity in unexpected places.”

That is the point, says Ms Kenyon: “The National Gallery does not have a monopoly on expertise. Teachers are inspired by a work of art and exercise their creativity thinking about how they can use it in their school. That stimulates the children’s creativity and their response.”

The next Take One Picture exhibition opens at the National Gallery on April 20. The featured painting is ‘The Stonemason’s Yard’ by Canaletto.www.takeonepicture.org.ukFor details of teachers’ courses,tel: 020 7747 2424 www.nationalgallery.org.uk