Supported by the Bank of Scotland, they had enjoyed a week of intensive playing and learning at St Andrew's College, Bearsden. Mid-heatwave, all the windows were open and the sounds of smoochy sax and funky bass line filled the air. According to course director Richard Michael, some had to have their instruments taken away from them to persuade them go to bed.
Mr Michael is the dynamo powering this event and the only man I have ever met who can say "You get the vibe?'' without blushing. His passion for every aspect of jazz culture - and that includes the slang, you dig? - is infectious, whether he is enthusing over a coffee in the staffroom, doing outreach work in Stornoway, or dancing in front of a big band.
"In the Sixties I played the pubs in Aberdeen, constantly getting shouted at for not being able to read, or getting the chords wrong, and I thought: there must be an easier way to learn.'' He has dedicated much time since to perfecting his own teaching method, and bringing jazz into the mainstream of music education. Most recently he has been persuading the Associated Board that a graded jazz piano exam is a good thing.
Fear, more than anything, seems to have kept jazz on the margins. Many teachers lack a working knowledge of the music and hold the common belief that you should keep jazz until after you have acquired a solid instrumental technique. Not so, insists Michael. The kids involved last week represented a wide ability range, and the three bands (NYJOS 1, 2 and 3) reflected that; of course not all of them could hope to turn out smooth,well-turned solos, but there are seeds to be sown, and the earlier the better.
Like jazz itself, Michael's technique is built around rhythm and phrasing.He aims to instill a solid sense of the beat and how to work against it: no child in the place should be capable of going dah-dah-dah-dah where dat'n'doo'dat will do dat. If you ain't got that swing, after all, you're lost. Once you have it, then you can go on to learn 12-bar blues and 36-bar songs, the different styles and their demands.
Michael is a persuasive advocate of the potential educational benefits of jazz. It is so manifestly cool that people practise hard and willingly. And it is hard work, demanding intense concentration, attentiveness and invention. The element of unpredictability heightens individual responsibility, so there is no hiding at the back of a section.
Jazz could also encourage creative musical thought in paragraphs rather than bars (even if many jazz players prefer the bars). One of the most difficult things to convey to young musicians is the notion of musical structure: not sonata or rondo form, but the way chords weigh against each other to create a sense of musical space and time. With a heap of notes to get through, it is often neglected, but in jazz the standard structures are extremely transparent, making it easier to see the end from the start. That horizon-stretching experience can enrich all music and encourage playing - and thought - of a purpose and direction too often lacking in young musicians more dependent on other people's notes.
Finally, there are those intangible social benefits: Michael's claim that "I teach confidence. After all, you're standing in front of a crowd of people and you have to play something." Certainly these musicians did it and looked cool and pleased to be there.
Many of these benefits were in evidence at the final concert, even if it raised the eternal question of performance and education. The educationist in me applauds allowing all 81 musicians their moment: the spotlight is such a potent inspiration to achievement. But the jazz-lover was disappointed that just as NYJOS 1 (the best players) were really getting hot, they had to make way for the next band. The gear shift from sheer swinging pleasure to admiring first, stumbling efforts cooled the temperature to neither band's benefit. Perhaps a separate performance is needed for the lesser players, allowing NYJOS 1 its own platform. After all, classical cousins NYOS allow only players of a certain standard, and both their pleasure and their audience's is enhanced by the fact that they are offering a musical product to match that of many professionals.