What puts the fizz in cola?

25th April 1997 at 01:00
Science in Action BBC 2, Thursdays, 1.25-1.45pm. Rpt Tuesday June 17, 2.00-3.40am. Age range: 11-13

Getting the right balance between education and entertainment isn't easy, and many educational programmes are either worthy but dull, or fun to watch while adding little to a student's knowledge.

But Science in Action is one of those rare series that both keeps pupils entertained and helps them understand a number of scientific concepts.

I showed them to children of the designated age range, as well as those a few years younger, and all of them enjoyed the experience - and learned something. Each programme lasts around 18 minutes and follows a basic format.

The action starts in a warehouse where the female presenter Stella (Kate Maravan) is working on a large space rocket. She keeps getting disturbed by three children who are puzzled by some observation (such as why a balloon won't inflate when it's inside a bottle). Stella and her friend Trish get on the case through a series of interesting experiments and demonstrations.

The first programme "Air" (April 17) used a number of clever demonstrations to show how air pressure worked. A balloon full of air was dipped into super-cold liquid nitrogen, which turned the gases to liquid air. This made the balloon collapse - as the air got warmer, it expanded again. This was supported by a funny cartoon animation which clearly showed what happened to the air molecules.

In another experiment, balloons, cream cakes and cola drinks were put inside a pressure chamber and air added. Superimposed arrow graphics showed how the air pushed on the objects inside the chamber, making the balloons collapse, the cream cake slide about, and the cola fizz.

"Light" (April 27) takes Trish to the Road Research Laboratory and a demonstration on the reflectivity of materials. We learn about retro-reflective materials, which bounce the light from car headlights back to the driver, and observe a man wearing an incredible illuminated vest.

You also discover how to measure the speed of light and how stars are so far away from Earth (complete with Trish pedalling on bike through the universe).

Do you always wash your hands after going to the toilet? Watching "Microbes" (May 1) should convince you of the wisdom in doing so. Microscope slides and petri dishes show how colonies of bacteria grow on our hands and clothing; a lovely experiment using peas demonstrates just how fast bacteria can grow, given the right conditions.

My main gripe here is that pupils aren't given a clear idea on how useful many microbes are, although there are several references to some being harmless. It would have been nice, for example, to have seen how microbes are important for food production and digestion.

Even so, the programme finishes on a subject that many youngsters will have an abiding interest in - spots and acne.

And so from spots to salt flats. "Mixtures" (May 8) looks at solutions, by way of the amazing salt flats of Utah. A series of experiments here helps pupils understand terms such as dissolve, evaporate, insoluble, and saturation (when a solution can't dissolve any more of the solid). Using a massive teaspoon and giant molecule models, Stella shows how things dissolve, and why we can put sugar into a full mug of tea without it overflowing.

Pupils will enjoy watching these programmes. The presenters are enthusiastic without being over-the-top, understandable without being patronising, and really help students grasp concepts quickly and easily. This series is highly recommended.

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