Suspension Bridges and Big Bubbles: A Hands-On Science Fair in Scotland

"Mum! Mum!" The five-year-old Scottish boy says, desperately trying to catch his mother's attention. "MUM! Did you see that one? It was GI-NORMOUS!"

Heavily engaged in the art of big-bubble-making, the boy goes back for more. His is just one of many activities available at the annual Edinburgh International Science Festival, a two-week event that runs through April 6.

Aimed at the general public (particularly its younger members), the fair takes a hands-on and intentionally low-tech approach. Adults will find much to interest to them. But for children, the idea is to engage them at a time when they see science as entertaining and fun. Communication is the focus - by excitement, and through human rather than high-tech interaction.

The Science Playcenter, where the boy is bubble-making, is an area for three-to-five-year-olds. It offers "scientific" adventures like talking down "audio piping," making shapes with "space-mud," or learning "about gooey things."

The playcenter is safely separated from the rest of the Science Works venue designed for older children.

The venue - the Scottish capital's Georgian Assembly Rooms - is inundated with children (parents in tow). They take a journey to the center of the stomach. They use computers to make their own tartan or learn about black holes in space. They pan for gold; generate electricity; battle heroically to construct a confusion cube; make a fossil; lay hands on a plasma dome; polish a stone; find a magnet; "see" speech.

Some of the events are performances, presented with various degrees of professionalism. They definitely involve their audiences. Participation is everything.

The performer of "Mathemagics and Structures" is the bright voiced, youthful Anna Bambridge. Since January she has been taking her show around to schools as part of a education program integrally connected with the festival.

Today, her audience is populated with some 60 students, plus teachers, from Forthill Primary School in Dundee. She combines entertainment with instruction, and has the audience eating out of her hand.

She finds plenty of volunteers - to cut corners off a triangle, to help build a brick arch and then stand on it (to great applause) - even a teacher to perch on a board placed on several rows of upturned toilet-roll inners.

Bambridge makes the point that shape often has more to do with strength than the materials a structure is made of. She balances successfully on a fizzy-drink-can and then has a boy dent it with a ruler. It buckles instantly.

She brings out a model of a suspension bridge and shows how the natural way in which a rope or chain hangs from two points, with all its parts equally stressed, can provide an effective means for suspending a bridge. The load is shared by many points.

"So," she says to the children, "the next time you go over the Forth Road Bridge, you will remember how it works."

Since 1989, the fair has been part of this city, which is better known for its elaborate summer arts festival.

Overall attendance was 148,000 last year. This year, thanks to an attempt to move the fair in a more popular science direction, organizers are are expecting 170,000 to 180,000 attendees. So far, many events have sold out.

At "Secrets of the Theatre Explained," intriguing effects are the source of the children's queries.

* How was the device made that produced smoke rings?

A pliable skin is stretched over one end of a plastic garbage bin, which is on its side; a smoking pellet is put inside; then the skin is pushed to make the rings puff out.

* How was the noxious-looking liquid made to bubble and smoke?

With carbon dioxide, the same gas that makes drinks fizzy.

* How was the girl behind the screen invisible, and then suddenly visible?

The lighting was changed. When the screen is strongly front-lit it reflects all the light; when instead the girl is lit behind the screen, she can be seen clearly through it.

Participation is a big part of this performance. One group makes sound effects into mikes - a creaking door (a cork twisting in a bottle), rushing wind, light rain, a bat flying (an umbrella being opened and shut). All good, spooky fun.

Lack of high-tech may be one reason few young people over age 14 are around. Maybe such unsophisticated stuff is beneath them.

But for those ages 5 or 55 who can't tell plasma from plastic, it is both enlightening and fun.