The 10 and 11-year-old pupils of St Mary's school are buzzing with excitement. Who wants to ride the stationary bike? "Me!" they all yell in unison. The chosen boy starts to pedal furiously. As if by magic, the crude radio hooked up to the bike's flywheel starts to play raucous rock'n'roll.
What does this demonstrate? Not magic, but the appliance of science. The boy on the bike converts his potential energy into kinetic energy, which, in turn, is converted into electric and chemical energy. The human radio exercise is just part of a new science course offered by 3D Education and Adventure's outdoor activity centres.
"If you can capture kids' imagination you can teach them anything," says 3D science co-ordinator John Winder.
Take the exercise designed to show how hydro-electric power is generated.
Students are presented with a jumble of tubes, a water-wheel and a dragon's head. If they have absorbed their lessons about the five different forms of energy, and if they engineer an efficient design, they will be able to make the water flow fast enough to turn the water-wheel. The wheel's rotation creates an electric current which - presto! - lights up the dragon's red eyes. And the children's eyes too.
Throughout the exercise, the instructors challenge pupils to think creatively about the knowledge at hand. Their pride in achieving their goal is there to see.
"Because they're enjoying what they're doing, it's hard for them to realise that they're learning," explains Nigel English, 3D's marketing manager. "We often say it's science with chips, with the adventure being the chips."
The outdoor adventure company decided to take science outside the classroom when it noticed that teachers found it difficult to teach certain parts of the curriculum. It launched its course last September after 18 months of development. Schools can now explore the subject - following one of four themes - on a scale that can't be replicated in the classroom.
The Mission to Mars theme sets the children the task of colonising the red planet. They explore the relationship of the planets - especially the Earth and its moon - to the Sun; they make water-rockets to get to grips with the workings of space travel; and they try to solve the problem of how to produce oxygen in an alien environment.
They explore astronomy in the Star Lab, a mobile planetarium showing projections of the solar system, the galaxy and the night sky. This is often an evening activity for obvious reasons.
The Eco Adventure theme focuses on the sustainability of the Earth's resources, and ways to harness natural sources of energy. Students study how solar, wind and water energy is used to produce electricity; the interdependence of plants and animals; and pollution.
The citizenship game encourages children to build on this knowledge: they design a settlement that does not cause imbalance in the environment.
"Seeing them all work togetheris impressive," says Sarah Owen of St Mary's school in Brixton, Devon.
The Forensic Adventure sees children called to a crime scene to gather and investigate the evidence at hand.
Finally, the Fields of Force Adventure challenges children to use experiments involving light, sound, magnets and electricity to create a security system to protect a priceless artefact.
3D adventure has three sites in Devon, Dorset and the Isle of Wight. Prices per pupil for the science courses range from pound;75 during the low season to pound;233.Contact: 3D Education and Adventure, Richmond House, Richmond Road, Brighton BN2 3RL; Tel: 01273 676 467; www.3d.co.uk