Harnessing energy from the sun proved tricky when school children tried out solar ovens they had made.

Youngsters at Milstead and Frinsted School spent the day experimenting with different ways to generate power last week.

They had planned to melt marshmallows in tin foil-covered upturned umbrellas but, as has been the case all summer, there was not enough sun.

More successful experiments included pupils pedalling on a bike to create electricity, used to power machinery such as a radio, a bubble machine and an inflatable.

Other workshops saw them make greenhouses from cardboard and cellophane and water wheels.

Pupils also buried a time capsule, packed with items chosen by each of the three classes, including a jubilee coin, articles about electronic gadgets such as an iPad and a book bag with the school's logo on it.

The position of the capsule was marked by the planting of an oak tree in the school field, which had been grown from an acorn by teaching assistant Karen Brown, who organised the eco-day.