Liberton High, on the south side of the city, tries to ensure that education overcomes social and economic disadvantage. But the behaviour of this group of 12-13s was so disruptive they were at risk of, at least temporarily, losing that chance.

The project with Young People Speak Out has shown them there is an alternative, that they can cope with a rigorous discipline and that they can work creatively within a group.

Liberton is among 37 mainstream schools and special units in Edinburgh and the Lothians taking part in an evaluation of the agency’s work in schools. Preliminary findings, due to be published next week and based on questionnaires completed by staff in six schools, show that of 36 pupils taking part in a YPSO project in the past year, between a fifth and a quarter have improved attendance, engagement in learning and behaviour.

Ann Donaldson, a guidance teacher at Liberton, says: “Discipline and patience don’t come easily to them. It was good they had to watch demonstrations and listen to instructions. They also had to make plans. Storylines, production and acting roles had to be decided on - and shooting sessions painstakingly set up.

“Although they were given regular feedback on their work, they did have to cope with the realisation there was to be no instant gratification. A lot of hard work had to be put in first.”

The result is not just a video. “As they progressed through the project the boys all became much more organised. They were also more ready to accept that the praise they were given was genuine, and that they did do well.”

The evaluaton includes the reactions of pupils. Of 75 questioned, 68 per cent felt they had grown in self-confidence, 73 per cent felt better able to speak up in a group setting and 44 per cent said they now knew how to set goals and achieve them.

Not surprisingly, the video projects often focused on themes of murder, mystery and mayhem. But 16-year-olds at Dunedin, an independent school in Edinburgh for what some term the “educationally fragile”, came up with a video whose message is that alcohol is not worth the havoc it can wreak through unprotected sex, not to mention poor football and self-defence skills.

All four pupils involved have all been awarded an Access level 3 award in “working together”.

Most schools choose two-hour weekly sessions over six to 10 weeks, although particularly positive evaluations followed residential experience.

Pete Gregson, manager of Young People Speak Out, believes that class teachers should be involved and a course has been mounted. “We want the teachers to take part so they can share, then carry on the same set of dynamics with their pupils that we aim to spark off.”

The agency, which used to specialise in work with community youth groups, expanded its role in schools last year thanks to a three-year pound;230,000 social inclusion award from the National Lottery Charities Board.

Gwynedd Lloyd, senior lecturer in equity studies and special education at Edinburgh University, says: “It’s a context in which the pupils achieve success in personal and social terms, and in which they feel particularly valued.”

The agency is uncertain how to continue its school work once the Lottery cash runs out. Ms Lloyd warns: “There are too many projects in this field which are blighted with short-termism.”