Music Live is one of those huge events that is so widely advertised that one can be perfectly aware something is going on without having a clue what it is all about. This time last year, you might remember, Music Live’s jolly logo came to Glasgow for five days in which the BBC either broadcast or catalysed more than 150 live concerts. Now it has been boosted by a pound;10 million cash injection from the BBC and innumerable sources of partnership funding, not least the National Lottery.

But what is it? In essence, it is a long weekend of music, from May 25-29. To cherry-pick some highlights, there will be a free performance by the BBC Scottish Symphony Orchestra of Messaien’s epic homage to the earth, Des Canyons aux Etoiles, the first broadcast for more than 20 years of Leonard Bernstein’s extraordinary Mass, concerts at dawn and dusk in Orkney performed by the Orlando Consort and the BT Scottish Ensemble and it will culminate with an unprecedented 24-hour schedule of continuous live music on BBC 1 and 2.

However, more than 95 per cent of Music Live is not being broadcast. Some 6,000 events have been registered in the UK, 600 in Scotland. They include such disparate events as round-singing in primary schools, chimes performed by a fleet of vintage ice cream vans and a festival in Kirkmichael organised by the jazz guitarist Martin Taylor. This compendium of street-level music-making will underpin what Scottish co-ordinator Svend Brown calls the “aspirational events” to be broadcast.

Education authorities have been quick to see the possibilities of getting children to participate. In Edinburgh, Abbeyhill, Preston Street and Royal Mile primary schools have taken inspiration from the volcanic surroundings of Arthur’s Seat to perform what is billed as a “sonic volcano” in the amphitheatre space in front of Dynamic Earth, the city’s audio-visual showcase of the planet’s history. Guided by the music animateur Jennifer Martin, the children will depict the various stages of volcanic eruption, from the early tremors to the tidal wave as molten lava pours into the ocean.

By contrast, Dowanhill Nursery school will perform music from around the world in the Kbble Palace of the Botanic Gardens in Glasgow. On the island of Rhum, the primary school will add its voice to “A Round for Scotland”, one of Music Live’s themed projects in which pupils all over the country have been invited to write new words to the familiar round “Fr re Jacques”.

One of the noisier contributions will come from East Kilbride, South Lanarkshire, where the music educationist Steve King has been working since last autumn with St Andrew’s High, Heathery Knowe Primary and St Louise’s Primary on a “trash band”. The instruments are made out of recycled materials, more exactly materials not normally used for music, such as plastic drums, gas pipes, car wheels and steel sheets.

The instruments, Mr King says, have all been constructed by the children, although he concedes that he sawed some 20ft gas pipes - “but they chose the notes” - to create something that sounds “just like a bass guitar when struck with a soft bat”. The overall sound of the band, he claims, is recognisable as music, “powerful, heavy, Third World stuff”.

It is an atypical contribution in that the project was well under way before it signed up to Music Live, but the BBC now plans to record the trash band’s performance in East Kilbride shopping centre for later broadcast.

Music Live is characterised by intertwined themes. The first day has been billed as “young music makers day”, while the Prince’s Trust has used the event to launch its Hidden Talent Network.

An instrument amnesty for Music Live is a noble attempt to extract instruments from those who don’t need them for use by those who do. Mr Brown was worried that he might end up with 2,000 recorders, but so far his fears have been unfounded.

Another theme is “Beat This”, in which the country will be united by a series of “drumming beacons” for 20 minutes at noon on May 29. At 10pm that day the entire country is invited to sing Lou Reed’s “Perfect Day”, with a new orchestral arrangement being broadcast by the BBC Scottish Symphony Orchestra from the Glasgow Royal Concert Hall.

Music Live information line 08700 100125; www.bbc.co.ukmusicliveTo be part of the two record-breaking events on May 29 - the drumming or the singalong - or to put your school music events on the website, call Svend Brown, 0131 248 4070