The noise is first thing that strikes you. There are cackling geese and clucking hens, bleating goats and sheep, and a cock that rarely pauses for breath. Only the pigs seem subdued until someone approaches their pen, provoking an explosion of squeals and grunts.
If it wasn't for the ranks of Victorian terraces and the occasional tower block that catch your eye when you look up, you could forget you are in the heart of Bristol. This is Windmill Hill City Farm, one of over 60 working farms nationwide sited on once derelict urban wasteland. Supported by the National Federation of City Farms (NFCF), all are managed on sustainable principles, and run by and for the local community.
They welcome thousands of young visitors each year. "A lot of city children have no opportunity to learn about animals or the environment," says farm co-ordinator John Purkiss. "Things we take for granted come as a revelation - like the fact that sheep produce wool, or goats milk. Some of them don't even know where their ham sandwiches come from."
Besides its livestock and crops, the farm has several ponds, a nature conservation area and a variety of hedges and trees that provide a natural habitat for insects, birds and other wildlife. It also has a craft centre and an adventure playground.
"A visit to the farm is always fun," says Mr Purkiss. "But if you plan it in advance and follow it up afterwards, it's a much richer experience."
Chrissie Fenton of Victoria Park Infant School has made numerous trips to Windmill Hill, which have spilled over into the classroom. Her pupils have made compost, built a wormery, dissected an egg, and hired a farm incubator to follow the transformation of egg into chicken.
"It has a terrific spin-off for social and personal growth. One girl who couldn't relate to other children was fascinated by the eggs and chicks, and months later remembered every detail. She was sometimes aggressive towards classmates, but she never once harmed a chick."
Her school uses an NFCF information sheet on exploiting farm resources across the curriculum.
"One class did a wonderful technology project building a hutch that was watertight and windproof. Others did lots of science and maths - growth charts for example, and for geography we did a trail and drew maps. One of the best things to come out of our visits was the quality of creative writing - singled out for praise in our OFSTED report."
"We have around a dozen activity sheets aimed at key stages 1 and 2," says Mr Purkiss. "If we know in advance that someone wants to focus on a particular topic, we'll always try to help. Even a simple request like permission to feed the animals requires notice so we can make sure they're hungry."
"Each farm is unique," says Ian Egginton-Metters, director of the NFCF. "Some have packs on areas of interest, others organise events around themes, such as sheep shearing. Not all have a full-time educational worker, but they all give teachers support."
The NFCF has a few materials of its own, although these are mostly classroom-based, he says. "A lot of teachers have no experience of handling animals. If they start in the classroom, we hope this will fuel enthusiasm."
The NFCF has collaborated with the Food and Farming Education Service on a guide to teachers' resources, free from the Food and Farming Education Service, which also publishes an educational pack Learning from the Land (pound;10).