"Within an hour they can play a simple tune," he says. "Within a week they can be good enough to perform in assembly."
And the instrument? A simple C harmonica, highly portable, nicely finished and desirable in its own box, with a simple system of notation devised by Douglas King. At present, very few, if any, schools in the UK teach harmonica. Yet virtuosos like Larry Adler fill concert halls with it, folk artists play it, and concertos have been written for it. And it only costs Pounds 6.
Armed with a bunch of harmonicas, his own musical expertise in guitar, banjo, harmonica and more classical instruments like violin, cello and piano, Mr King sets off for Oakfields Junior School in Gateshead where the head has invited him to enthuse a class of eight to nine-year-olds and their teacher.
The key (so to speak) explains Mr King, is to let children play by ear. "If they play by ear - and it must be a tune they know, of course, even with the classical instruments if you are playing by ear - then they quickly get the confidence to find their own way around the instrument. Even after the first session when we all learned "Kum Ba Ya", a lovely simple tune which they all know, they would take the harmonicas home and come up to me the next day and say, "Look, I've found this tune'."
Having simplified the notation to a series of directional arrows for left, right, louder and softer and to B(blow) and S(suck), the barrier of "reading music" is crossed in a bound. The harmonicas are 24-hole, diatonic models. Since it requires more technique to play single notes, the children are encouraged to blow chords and as the chords are thirds, even if a few players are slightly off, they will be in harmony with the main tune, laid down by Mr King on guitar and harmonica. Success is assured.
The quick success factor is crucial. Schools following the national curriculum requirement to give children the chance to play a musical instrument have tended to abandon the traditional recorder group to a few dedicated girls and give boys the chance to bang on percussion. But, says Douglas King, the harmonica, which has a "cool" rock-star type image, is also boy-friendly and can open up a child's own musical sensitivity. "They particularly enjoyed playing with their eyes closed," he says. "As they develop a facility for playing by ear, they will be able to access any tune they know - and it is surprising how many tunes they find they do know."
It took one lesson a day for a week to get a class of children to learn 10 tunes on the harmonica. It will only take a day, says Mr King, for a teacher of reasonable musical ability to learn how to play and how to teach. The rewards will be pretty much instant too, ranging from the thrill on the faces of the children in assembly, to the pleasures of shared music-making with other instrumentalists and the first explorations which children begin to make moving on from the harmonica to other more complicated instruments.
"But," stresses Douglas King, "that's not what I am trying to do. My goal is to get children to enjoy music and to be able to play it."
According to Andrew Hearndon, headteacher of Oakfields, who was "quite surprised", the children made "very satisfying" progress. According to the children themselves, "it's really fun making up your own music".
Douglas King can be contacted at Educational Developments, 24 Wallcote Avenue, London NW2 1AU. Telfax: 0181 455 1383