How many creative directors does it take to change a light bulb? The answer, apparently, is two - one to come up with the concept and the other to say it’s been done before.

This and other mysteries of getting ahead in advertising are currently being pondered by the four to 15-year-olds who hope their campaigns in one of four categories, print, radio, TV or Internet, will grab the nation’s attention for at least one week in November.

The effort is part of a Library Association competition, The Big Idea, which asks young people to think up a campaign to entice others through library doors. The winning campaign in each category will run during National Libraries Week (November 3-9).

To do this, says one of the competition judges, Mark Wnek, pupils will need to use their own mental library containing all the ideas they’ve ever had. Mr Wnek, one of the brains behind the Pure Genius campaign for Guinness and creative partner in the agency Euro RSCG Wnek Gosper, puts his success down to “being interested in everything, but nothing in particular.”

He says: “You have to deliver your message in such a fascinating way that it grabs attention but still states the message clearly. You take your brief and call on all kinds of references and tangential ideas. In this case the brief is to sell libraries to kids who would rather go to football matches or nightclubs.”

The emphasis is firmly on original ideas rather than technique or access to technology. But a closer look at the process, including industry guidelines and related issues (such as the portrayal of children, women and men in ads) would be a useful spin-off.

Role-playing the development of an idea in an ad agency might also help the creative juices to flow, and brainstorming exercises would work for all age groups (the judges will take age into account).

Children’s book illustrator Mick Ink-pen, one of the judges in the print category (covering posters and magazine ads), is an expert on great ideas - especially on rejecting them. In the competition briefing notes he warns: “Design is about trying out ideas and changing them - sometimes throwing them out of the window. Be prepared to have a couple of goes over a few days. ”

He says: “Constant editing and rejection is something you have to learn. Younger children don’t do it so well - but then they have the advantage of fresh, raw ideas. It’s important these aren’t crushed.”

More designers and advertising executives are being recruited to run workshops through library authorities, which are organising and judging the initial rounds in the print, radio and Web site categories (Blue Peter is running the TV category as a separate competition). For example, North Yorkshire librarians are being trained by BBC Radio York to run jingle-writing sessions. Touring library-based workshops on writing, cartoons and illustration are being organised by Hodder Children’s Books, which is sponsoring the competition with Microsoft. Many events will be open to school groups, although some may spill into summer holiday programmes (the closing date for entries is August 22).

Whole-class entries are welcome but the work is particularly suited to small groups (many of the most successful advertising campaigns have mainly been the work of two people - a copywriter and a designer or art director). Just don’t let them go out to lunch together.

The Big Idea competition starter kit for schools includes briefing notes and a Microsoft CD-Rom sampler. Limited number available: fax requests to Anne Sarrag on 0171 436 7218. Entry forms are also available from children’s libraries.

For details of competition-related workshops in your area, contact the head of your local children’s library service.

The Library Association produces a free schools information pack which includes details of useful publications: Information Services Department, The Library Association, 7 Ridgmount Street, London WC1E 7AE. Tel: 0171 636 7543, fax as above.

National Libraries Week has a Web site on http:www.fdgroup.co.ukla. htm The Advertising Association’s information centre has produced a set of student briefings on aspects of advertising which can be ordered by larger schools or libraries: The Advertising Association, Abford House, 15 Wilton Road, London SW1V 1NJ