When the Prime Minister was asked to sing in China, his wife had to come to his rescue. Not that Tony Blair does not sing; but in our culture, singing in a public place that is not a stage is generally seen as undignified, done by beggars and drunks.

However, during the Edinburgh Festival the world is turned upside down. Choirs sing on the pavements, cars and buses make way for street theatre and the city becomes a campus for the performing arts.

Teachers know that a week on the Edinburgh campus, performing and spectating, is worth years of school work.

The American High School Festival, now a staple of the Fringe, comes year after year, bringing school theatre groups who compete all over the United States for the privilege of inclusion. Some years as many as 1,000 young people come, in two groups, each spending about 10 days at the festival.

The schools sometimes have to raise funds for two years to collect the money for their production, travel and the Crown Plaza Hotel venue expenses.

“There have been disappointments when the kids have raised the money and then fears of terrorism have cancelled their trip,” says Amanda McRaven, of Live Arts in Charlottesville, Virginia, “but that’s happened less this year. Competition for places is fierce, so it is a great honour to be chosen.”

This is easy to believe, having seen the Theater of the Performing Arts at Miami Northwestern High School awesomely sing and hoof their way through Ain’t Misbehavin’, the Fats Waller tribute revue. I had to be convinced these were 18-year-olds; some of them had the voices, stage presence and shapes of people twice their age and their performance seemed more Broadway than Miami.

“You’ve got to remember the musical is the American theatre,” says Ms McRaven. “We drink it in with our mother’s milk; it’s in the air we breathe.”

Her remark glances at a characteristic of the American High School Festival, that its stock-in-trade is the musical, with all the blandness that might imply.

The Fats Waller revue had no other narrative than the songs’ lyrics, while the programme hinted at the background stories of how racism denied opportunity to the black community except in the “improper” performing art and how black artists therefore came to invent what has become Western popular music, and the biography of Waller, who wore the masks of tragedy and comedy in his brief career.

I thought I detected cracks in the blandness this year, with shows about being workers “who punch a clock and the boss” and shootings in schools. Ms McRaven agrees that this is a growing trend as more schools create their own plays and rely less on Broadway scores. It would be good to know that studying on the Edinburgh campus has helped this change, for youth-centred plays are the norm for their UK counterparts and the rarity of a musical is likely to be the bitter-sweet anti-war satire of Oh, What a Lovely War!

Forth Children’s Theatre chose this for their festival piece, as did Leicestershire Youth Arts, the company that has done so much to establish its college on this campus. It has been coming since 1979 and to the same venue for 23 years, overcoming the 1992 spending cuts that put an end to the local education authority sending school groups here. That’s when the newly-retired curriculum adviser Robert Staunton created the unfunded LYA as an umbrella organisation to continue the work.

Leicestershire-wide arts projects create the plays and musicals to bring to the Fringe and the year’s work of all the participants is measured against performance criteria. Those aged under 14 achieve Youth Arts Certificates of Achievement and older participants follow the Open College Network at levels one, two or three, the last being equivalent to a CD pass at AS-level, all under franchise from Leicester College. In this way, the Fringe almost becomes an annexe of Leicester College, a campus where they can gain qualifications in theatre performance, stage management, technical theatre and stage design. Proof of these advantages were all around.

Among LYA’s six productions this year were inventive interpretations of two John Godber comedies, Teechers and Bouncers. The latter is a celebration of the common man and woman’s Friday night, a voyage from work to hairdresser, pub, club, takeaway and 3am blue video. It was an admirably taut and dynamic production with a cast of four who demonstrated the virtues of the LYA structure.

One of the quartet and co-director was Chris Hill, who has progressed from being a schoolboy participant to qualifying and working as a drama teacher and now comes to the Fringe as the LYA’s venue manager. Another actor was the compelling Richard Kidd who, after several years of the Fringe and LYA, starts an acting course at London’s Guildhall School of Music and Drama next month.

The educational benefits such organisations reap are as readily available to single schools and youth groups. Bishop’s Stortford College brought its drama club’s production of Much Ado About Nothing, set in Britain in the weeks following VE Day. Although the setting did little to illuminate the play, the artistic and technical direction and the exemplary wardrobe gave the performers a confident platform and a precise cultural reference point for the social behaviour, dancing and wearing of trilbies, although the young ladies’ ease with bondage seemed to me to be an anachronism.

The confidence of the members of Newbury Youth Theatre, appearing on the Fringe for the seventh year, stemmed in part from their having shared in devising The Control Experiment, a warm-hearted and spiritedly played investigation of what it is like to be a victim of attention deficiency hyperactive disorder. I learned much, not least that ADHD sufferers are prescribed cocaine as a downer, which some then sell in the playground, but then, as I say, the Fringe is an education.

LYA’s Oh, What a Lovely War! until August 23Teechers, until August 23Bouncers, until August 24Much Ado About Nothing, until August 23www.edfringe.com Tickets, tel 0131 226 0000