Eden Project’s spectacular biomes nestle like transparent golf balls half-submerged in a former china clay pit near St Austell, an amazing sight even through freezing drizzle. You approach at a stately pace in carriages pulled by a tractor, winding slowly between the pit’s 60 metre deep steep sides. But nothing prepares you for the sheer size up close.

Inside the humid tropics biome, surrounded by plants from the Oceanic islands, Malaysia, West Africa, and South America, it’s as if someone has whipped you into the Tardis and transported you to the rainforest.

Humid means hot and sticky. After 30 seconds, everyone is shedding their coats. A long way above your head- the biome is as high as 11 double-decker buses - you can hear a waterfall.

The plants you can see from the footpath range from tiny to enormous and spectacular, or simply beautiful, like a pink-tinted pineapple and a prickly pear.

You wander through the rainforest and a chorus of “wows” drifts back. After an Oceanic Island dwelling, you pass a rice paddy, pineapples, coffee beans and cocoa pods. “I wish we could live here,” says a wistful child. Some plants look familiar. Others, like the glossy black bat flower, definitely do not.

The Mediterranean biome uses sculpture well, but the plants obviously have a bit more growing to do. However, when we visited the large and orderly crowds were obviously impressed. Tom, 5, particularly liked the cacti and the bee sculpture outside. Isabel, 6, liked “the brightness of it all”.

Education is central to Eden - they want to promote a sustainable future by fostering understanding of the relationship between plants, people and resources.

Already links have been made between Cornish schools and those in Guyana, Cameroon and Malaysia.

Workshops linked to the National Curriculum range from story-telling and handling data, to studying living things in their environment and observing art in nature and architecture.

Eden is home to more than 135,000 plants and 4,500 species in the two covered biomes and outside planted area.

Local and national artists have provided sculpture, paintings, illustrations, mosaics and models.

There are guided workshops for groups from reception upwards. “Feast for the Senses” challenges the way we view the environment. The “Don’t Forget Your Leech Socks” expedition explores traditional and modern uses of tropical plants. The “Global Shop of Stories” examines tales about plants from British and all over the world. And there are teacher-led workshops and special events.

Neil Treneer of Cape Cornwall School, Penzance, took part in “Don’t Forget Your Leech Socks” with his Year 5 class.

He said the children were “gobsmacked and enthralled”. Kerry, aged 10, said: “It was interesting learning how Coke, chewing gum and chocolate were made from the plants.”

The Eden Project, a registered charity, ploughs any profits from visitor revenue into the Eden Trust to raise awareness of sustainable development and environmental research. The St Austell site was chosen, in part, to help regenerate that part of Cornwall. Goods and services are locally sourced wherever possible, and 290 jobs have already been created.

The biomes are the largest greenhouses on earth, and only slightly heavier than air. They took two years to build using the largest free-standing scaffold ever - 25 metres across with 230 miles of poles. In six months 1.8 million tonnes of earth was moved. The slopes had to be stablised with rock anchors. Because there was no earth, it had to be reclaimed from china clay and organic waste.

Visitor numbers have been as spectacular as the structure. Since Eden was completed and opened in March, 1,250,000 have visited, far outstripping a target of 750,000 set for the first year.

Jim Seth, deputy head of Sithian’s School near Redruth, came with Year 5 and 6 pupils. He found the project “stunning”. But Abby, Year 5, wanted three-dimensional models of animals and birds to make it realistic.

Thaissa from Year 5 said: “The workshop was more like a test, so if Eden would be a fun day out, less writing, less diagrams and more looking for things would be interesting.” Her classmate Stephen agreed. He had “an amazing day. I thought the biomes were fantastic, but the workshop booklet was like a test paper.”

Eden Project Bodelva, St Austell, Cornwall PL24 25G Tel: 01726 811911 Web: www.edenproject.comThere is parking for more than 20 coaches, the gallery doubles as an education centre and there is also a double yurt at the expedition centre where bags can be left. School parties should aim to arrive half an hour before the start of their workshop, and take plenty of water into the humid tropics biome.

Similar attractions Birmingham Botanical Gardens Tel: 0121 454 0784 The National Botanic Gardens of Wales Tel: 01558 668768 Wakehurst Place Millennium Seed Bank West Sussex Tel: 01444 894094