Even a sickly pot-bound house plant has its uses. Such a specimen, owned by Jane Swan White, geography and science co-ordinator at Harland first school in Merton, south London, proved perfect for illustrating how the tightly tangled roots cling fiercely to the soil.
Her class of six to seven-year-olds took part in a workshop led by the borough's arboricultural officer, Dave Lofthouse. He was at the school to supervise them each planting an acorn.
Now, a year later, most of the lovingly nurtured acorns have grown into oak saplings. Earlier this week children started planting the saplings out to help rejuvenate a piece of ancient woodland near Motspur Park.
Altogether around 2,000 saplings have been grown by 50 first and middle schools in the project. An additional 8,000 have been grown by other local groups. Sponsored by the London Borough of Merton and Railtrack, the project was organised by Trees for London, an environmental charity set up to help improve inner-city areas.
"We have used the project as the basis for a wide range of geography and science work throughout the school," says Jane Swan White. "Observing the roots of my potted plant led the children on to the role of trees in binding soil.
"We have also collected and planted other seeds for comparison, and use drama and videos as well as writing and art to highlight the issue involved. Hurricane Mitch in Florida made a timely appearance to illustrate our work on erosion, which can be a difficult topic for young children to understand."
The saplings have also been used to introduce older children to more complicated concepts such as sustainability and bio-diversity. What sort of trees would they grow into and how long would they take to mature? How old are the trees in the school grounds and how do they compare with those in a South American rainforest?
"They have provided the children with first-hand experience in the use of resources," says Jane Swan White. "When some of the saplings weren't watered enough, they began to wilt. And a few were dug up, probably by squirrels or mice."
Trees for London can be contacted on 0171 407 0888. Saplings Club for under-16s includes workshopsand invitations to tree plantings;subscription pound;10