The Upper Derwent Valley in Derbyshire, which winds through forests, moorland and farmland past reservoirs, is the most popular area in the Peak District National Park, attracting about two million people a year for pursuits such as walking, cycling, riding, fishing and bird-watching.

Managing the conservation of the valley at the same time as providing facilities requires a delicate balancing act, particularly as most visitors come at weekends and bank holidays. A group of 14 and 15-year-olds from Comberton Village College, Cambridgeshire, studied how this is done during a visit for their GCSE in leisure and tourism. “Sustainable management”, geared to GCSE, GNVQ and A-level, is one of several topics offered by the park authority.

By way of introduction, Zoe Connolly of the park’s education visits service gave the 18 students a talk on the area at the youth hostel in nearby Eyam, where they stayed overnight. After explaining that the three reservoirs had been created between 1912 and 1945 by damming the River Derwent, she asked them to consider what sustainability meant.

When the students arrived next morning at the valley’s Fairholmes visitor centre, she cast each of them as a member of an interest group - rambler, farmer, conservationist or watersports enthusiast. Everyone, including their geography teacher Piers Miller and two other staff, then got kitted out with bikes and helmets, as the day’s programme is based on a six-mile ride round the largest reservoir, Ladybower.

Zoe Connolly said: “We will be making several stops to consider an application for planning permission by a Mr Bigg to build a watersports centre on the reservoir. By the way, Mr Bigg’s son, Rodney, is a keen jet-ski racer.” And she handed out worksheets which would help everyone evaluate this hypothetical proposal.

Stopping first at Hurstclough viewpoint, everyone assumed their roles.

Arguments were soon being bounced to and fro. Jessica Van Kooyen, cast as one of the watersports enthusiasts, quickly realised she was going to have difficulty in defending her patch. “With all these people concerned about the environmental impact of jet-skis and the arrival of even more visitors, I’ve got a real fight on my hands,” she said.

At the next stop, opposite the proposed site for the centre, the students made a field sketch, annotated with notes that would be useful when they discussed the proposal back at school.

As they looked at the landscape, Zoe Connolly raised broader conservation issues about the management of the valley. Two villages had to be flooded when the reservoir was created to provide more water for Derby, Leicester, Nottingham and Sheffield; the conifers planted by the Forestry Commission to stop erosion and as a commercial crop were not as beneficial to wildlife as native broadleaf trees; and the burgeoning popularity of the area had created so much traffic that a six-mile stretch of road up the valley beyond Fairholmes was now closed at weekends and a free bus service provided.

James Ballantyne, speaking for the ramblers, said: “The noise of jet skis would ruin this beautiful place for walking. There would be oil spills, you’d have to widen the road and encouraging more young people to come would change the whole atmosphere.”

Back at Fairholmes, everyone except the watersports group voted against Mr Bigg’s application. But reverting to their own opinions out of role, opposition was noticeably less strong.

* The one-day course costs pound;7.50 plus pound;6 bike-hire per pupil.