AGUY. A girl. A target demographic. There was little chance Disney's High School Musical would fail. The television film has been watched by more than 37 million in the US, where its soundtrack has gone triple-platinum.

A range of High School Musical (HSM) stationery is already available, while monthly novels and dolls of the all-singing and dancing main characters, Troy and Gabriella, will follow. The film will be rolled out to more than 100 countries - it has already broken records in Australia and Asia - and arrives in the UK on September 22, when it premieres on the Disney Channel.

There is, it seems, little that parents of tweenagers - children aged between seven and 14 - in this country can do to stop their lives being invaded by songs including We're All in this Together and Stick to the Status Quo. A plot precis: Gabriella, an intellectual, and Troy, an athlete, meet doing karaoke on holiday. They click, but, being shy tweenagers, don't make a move. They meet again when she goes to his school, where both defy the expectations of their respective social types to audition for the school musical.

They both get the lead parts, become a couple and learn a lot along the way about being who they are and being accepted by their peer group. Indeed, parents of tweenagers may one day be able to watch their children act the story out, as Disney is issuing theatrical licences and expects 5000 school shows to take place by the end of the year.

The secret of its success? Precision marketing to the lucrative tweenage market. As the president of Disney Channel Worldwide puts it: "The tweenage market was very small 10 years ago, but now the market is being driven by this age group." This is as true of the US tweenagers as British. Nicola Stuber of Mintel authored a report earlier this year which detailed the extent of tweenage spending power.

"The average pocket money is GBP7.04 a week, but there's quite a big spectrum, " she says. "Some 10per cent get GBP15 or more a week, but that doesn't include any other money they might get from granny or for doing chores, and 10per cent get just under GBP2. Socioeconomically, more affluent parents give their children less money, while parents with less money tend to lavish it on their children."

Collectively, 11 to 14-year-olds enjoy a spending power of GBP1.7bn, while seven to 10-year-olds have just under GBP1bn. Further research has discovered that 61per cent of parents give in to the desires of their tweenage children when they demand DVDs and CDs. HSM is available on both formats, however, in mind of its target audience. Disney made HSM songs available online for tweenagers to download for free before the film premiered on the Disney Channel, thereby generating sufficient pre-release interest to achieve a record 7.7m viewers.

Not only has Disney understood the cold, hard facts and figures of its intended audience, the content of HSM has been designed to reflect the values of tweenagers. The plot of the movie may be familiar, but it's also one that neatly reflects research findings. "We did a lot of typologies for the group, " says Stuber. "A quarter of them make up traditionalists. Now they're the sort of children who are quite happy to do well at school, want to please their parents and go to university. Traditionalists like to feel part of a group, they don't want to stand out."

The second largest group were "individualists", who wanted to develop a unique identity. While these two groups appear polarised, they do have a common aim. As Stuber says: "Regardless of their personality type, friends and school are most important". The survey found that 60per cent of seven to 10-year-olds thought it important to belong to a group.

HSM could be said to straddle the two. The lead characters excel at school in different ways, want to be individuals but also want to be accepted as part of a group. Troy rebels against his father's expectations of him by singing and dancing. In doing so, he gives a fellow jock the confidence to admit his enthusiasm for baking.

HARMLESS fun? Perhaps, but some commentators have expressed dismay at the manner in which teenagers and, by association, tweenagers are being targeted. Alissa Quart, in her best-selling book, Branded: The Buying and Selling of Teenagers, revealed that up to 55per cent of American high-school seniors (the equivalent of fifth and sixth year) take on part-time work for up to three hours a day so they can buy "stuff". Quart regretted what she perceived as being the fundamental message that "the only way to participate in the world is to turn oneself into a corporate product".

In turn, this can be isolating for those who don't fit the mould.

Rebekah Willett, of the Institute of Education at the University of London, researches how children use digital media. She is American and recently spent time in her home country but managed to avoid HSM. "I go to a very isolated cabin and we have no news, " she explains.

Willett recently researched the cultural currency of the tweenager profile and interviewed young girls who would be categorised thus.

"The girls who fitted into the market term liked it, " she says. "They liked that they were identified as not yet teenagers and that they were their own beings - they liked to identify the innocent aspect of themselves as well as the sophisticated aspect. But not all fitted the category. One girl was basically the caretaker of her mother and three siblings. She didn't have the luxury."

That said, Willett is heartened by the fact that HSM fans have been posting their own versions of songs and dances from the film on online social network YouTube. com.

"It shows tweens taking that economic capital and turning it into something of their own, " she says. "It's not a marketing ploy - it's something that tweens want to do. If they are taking the songs and making music videos, then there's a DIY ethic. It's not an identical product, they did it themselves. It's not hugely subversive, but it is a form of subversion."

bethia. pearson@theherald. co. uk