In the 1940s, the late Sir Peter Scott, naturalist and wildlife artist, bought an area of marshland at Slimbridge in Gloucestershire to protect the wild fowl that depended on it. Today, the 800-acre wetlands conservation area on the River Severn estuary is a winter home for tens of thousands of migrating birds. It is also a rich educational resource which has increasing numbers of schools flocking to it.

There are nine trust sites throughout the UK which offer education programmes for all ages and abilities. Slimbridge, its headquarters, has become an internationally recognised conservation area and a huge visitor attraction. Its award-winning pound;8 million visitor centre, designed in the shape of a swan, can host large school groups. On a wintry day in January, 144 pupils from Fairford primary school in Gloucestershire are visiting.

“This is the best time to come because we have all the migrating birds,” says Sue Porter, the trust’s education officer. “We go from around 4,000 up to around 40,000 birds. It’s a really good time to see the different birds, how they feed, and how they act towards one another. And they are starting to pair up ready for the spring.”

Before heading off to the reserve, the pupils are handed worksheets, pencils and bags of grain for feeding. Then they step outside into a glorious whirl and cacophony of wildfowl.

The whole wetlands reserve is criss-crossed with paths and boardwalks, punctuated by information boards on the different species. There’s a tropical house and out on the fringes “hides” look out onto the salt marches of the estuary.

During their walk around, pupils look for different species of wildfowl including Bewick’s swans, coots, tufted ducks, flamingoes and Hawaiian geese, and tick them off their worksheet.

Back inside at the discovery centre in the main building, the children enter a mock supermarket designed to encourage them to consider how everyday products have links with wetlands, such as charcoal from mangroves, and aspirin, a chemical constituent of which is salicylic acid, found in willow bark. They also view simulations showing how wetlands work and sections explaining biodiversity.

In the centre’s lecture theatre, education assistant Charlie Pemberton gets pupils to simulate creating a wetlands habitat. With pupil volunteers and masks she demonstrates the different stages in the food chain. And she tells them of the risk to the wetlands if surrounding towns and cities use too much water.

They learn about the epic journey of the Bewick’s swans that have flown 3,500 miles from Russia, the special diet that keeps the flamingoes in the pink, and that the gentle ne-ne (Hawaiian goose) that’s been nibbling grain from their hands is the world’s rarest goose. Finally, the group get the chance to touch and feel preserved birds’ heads, wings and feet and see bird skeletons.

The day’s visit links up with the pupils’ work says Caroline Halcombe, the school’s science co-ordinator. “The whole key stage is looking at aspects of water in the environment, whether it’s water use and conservation or focusing on rivers, and this place is ideal for that.”

It’s also an easy site for schools to navigate. “I would rate it very highly. It’s fairly compact and well signposted with clear layout. I think the fact that they have walkways that are easy to walk on means that it’s all-weather. Even the access to the hides are reasonable for most children to manage and there’s good access for disabled pupils.”

One criticism from teachers on this visit was the lack of a guide to give children and staff more information on the walk. The WWT has since launched its new wetlands challenge programme which, Sue Porter says, will have staff accompanying school groups, and will make the walk around the wetlands into a more interactive challenge for children.

Slimbridge admission costs pound;3.25 per child. Teachers can log onto a new website at www.wwtlearn.org.uk to access a wealth of resources, including lesson plans, data, fact files and images. See also the Wildfowl and Wetlands Trust’s general site: www.wwt.org.ukvisitslimbridge