Britain's Royal Opera House beckons the next generation

The auditorium was awash with movement - over, under, up, down, and back and forth. The tumult was deafening as 2,150 voices shouted to friends. Clink-clunk went 10-pence pieces dropping into metal holders that secured red opera glasses to the backs of the seats in front, followed by squeals of delight as the glasses were used back to front to make everything distant and small. . . .

Could this be the revered Royal Opera House in London, with its red velvet curtains and sparkling chandelier, whose audiences usually talk in hushed upper-class accents and behave impeccably?

It could and it was. A multicolored sea of school uniforms was settling itself for a performance of Frederick Ashton's ballet ''Cinderella.''

In an effort to introduce the next generation of theatergoers to the worlds of ballet and opera and to encourage them, the Royal Opera House in Covent Garden annually offers six special full matinee performances at the greatly reduced price of (STR)3 ($4.50) a ticket. Ballet prices usually range from (STR) 4 ($6) up to (STR)19 ($28).

Included with the tickets are information sheets on how to get to the theater , costs of refreshments, program notes, and ideas for follow-up discussions back at school.

There were groans from program readers at the performance I attended concerning such discussion questions as ''What quality of movement or groupings of dancers does the choreographer use in Acts I and II to suggest the stars?'' ''Why is the production of 'Cinderella' important to the Royal Ballet?''

The buzz of excitement changed to cheers and catcalls as the lights dimmed and a neatly dressed man came through the curtains. ''During the second interval we will keep the curtains up so you can see how we change the scenery,'' he said.

There was a hum of approval which turned into chortles of laughter a few minutes later as the two (male) Ugly Sisters frolicked and fussed preparing for the ball. Ballet could be fun!

''I would be one of the mice that pulled Cinderella's coach'' (on stage all of 10 seconds) ''or perhaps one of the Ugly Sisters,'' said 11-year-old Scott. ''I certainly wouldn't be the Prince. . . .''

''I wouldn't mind playing the trumpet in the orchestra,'' commented his friend Mike. ''I wouldn't want to dance, but the Prince (Stephen Beagley) dances well.''

These two American boys, along with their classmates and teachers, down from a US military base in Cambridgeshire for the day, were in the crowded foyer in the second interval after the behind-the-curtain demonstration.

''I liked it,'' conceded Randy. ''I've never seen a ballet before and it's not . . . .'' He shrugged his shoulders rather than describe what he thought.

An East London sixth-former (aged 17), in a shiny black school blazer, said this was his first exposure to ballet. He was a little reluctant at first to admit in front of his friends that he thought it ''quite interesting . . . . I mean, they all have to be so fit, look at the men. I thought they would be sissies, but they have such strong legs.''

His friends all nodded in agreement, and one ventured to say that such legs would be an asset on the football field.

The Royal Opera House also has another project to interest children in the arts world - and is reaching out to them for financial help.

In a plan conceived by Lady Cave, a former dancer who is now the wife of the chairman of the big British TV and video company Thorn E.M.I., ballet schools throughout England have been sent a display sheet of cardboard, one foot square, on which nine octagonal-shaped 50-pence pieces have been drawn.

Underneath is written the plea, ''The Royal Opera House is the home of the Royal Ballet, the finest ballet company in the world.

''But backstage conditions in this 125-year-old theater are a national disgrace! Two ballet studios included in the new extension to be opened this spring will allow the company to rehearse at Covent Garden instead of two miles away at Baron's Court.

''To pay for this building, over (STR)9 million ($13.5 million) has been raised, but (STR)750,000 must be found within the next few months. Spring flooring is costly but essential.''

In other words, if each budding little dancer contributes just one 50-pence piece - no more, no less - then nine donations will provide a patch of new flooring for the Royal Ballet dancers the same size as the cardboard sheet.

''That's the equivalent of a bottle of pop and a bag of crisps (potato chips) ,'' said one teacher, ''so it's not asking too much of them.''

In return, each child receives a badge bearing a drawing of tutu-clad ballerinas surrounded by the words ''dancing children's appeal.''

The names of the donors will be recorded in the archives, and there has been talk of tours to see ''their'' floors.

The plan is being enthusiastically received.

The BBC children's television program ''Blue Peter'' followed through and produced a mini-documentary on what life is like backstage:

Washing tutus in cracked china sinks . . . the orchestra rehearsing in the crush bar with some players squashed behind pillars unable to see the conductor at all . . . a canteen that feeds 1,000 people yet can seat only 130 at a time . . . cramped and drafty wardrobe and storage departments . . . the ride of 20 minutes or more on the tube (subway) to the Royal Ballet's upper school at Baron's Court for classes and rehearsals.

The new extension, opened last July by Prince Charles, is helping to solve the problems, but as yet the money required has not been found.

The royal family is certainly pulling its weight in helping with the fund raising. Prince Charles has appeared in a film about conditions backstage which has been shown all over the country, and in 1979, Princess Margaret made a 17 -day tour of five American cities which produced half a million dollars for the appeal. (She also attended balls and a royal gala auction at Sotheby's.)

In the closing sequence of the film ''Prince Charles Backstage at Covent Garden,'' the Prince of Wales says, ''If we wish to preserve an artistic heritage, if we wish to encourage future musicians, opera singers, and ballet dancers in this country - and the reservoir of talent is immense - then we must be prepared to do something sensible about it. . . .''

The Royal Opera House is encouraging the younger generations to be aware of the cultural treasure around them.