Bursting with ideas;Science

24th April 1998 at 01:00
Bubbles are wonderful things - which is why Ted Wragg uses them to teach serious physics to infants

The secret of how to give young children an intuitive understanding of some of the most important and exciting concepts in physical science is simple and close at hand - the bubble. The ordinary household bubble offers a marvellous opportunity for extremely interesting and thought-provoking work in science, language and art.

What is more, it costs very little to give pupils the experience of conducting a simple experiment that has a unique added bonus - they end up cleaner than when they started.

Even very young children can develop an intuitive understanding of quite complex ideas. They learn what gravity does years before they ever discover its name. Babies in a pram, for instance, soon discover that if they drop something it will fall down, not up.

Bubbles offer the chance to learn intuitively while having fun. Surface tension, light, reflection and refraction, gravity, weight, shape, forces, pressure, the properties of liquids and gases are just some of the concepts they can explore. Pupils also learn how to observe, speculate and test ideas, all vital in science.

Infant children will learn intuitively through direct experience. Older children can cope with many of the specialist words and concepts as well.

Start the lesson by asking the children if they can transport water across the room without throwing or carrying it. Will we need to use some magic?

Then we make the bubble mixture, one part of good quality washing-up liquid to 10 parts of warm water. Use a yogurt pot. The children can make it up, while everybody counts up to 10 as the warm water is being added. Remember not to stir up the soapy mixture, or it froths up too much and spoils the activity.

First comes the speculation, or "hypotheses". What will happen if we make a bubble? Will it rise or sink? How big can we make one? What will it look like, what is a bubble? What is inside it?

Take any container with an opening at both ends, (a plastic household washing-up bottle with the bottom end snipped off is fine). Dip one end gently in the soapy mixture so that a film of soap forms across the opening, blow gently through the pouring nozzle at the top and a lovely big bubble will appear. It often works better if you make short, vertical incisions in the fat end where the bubble comes out. You can then shake it off so that it floats across the room. With a bit of skill, each of the children can create their own big bubble. Make a circle with thumb and index finger, dip it into the soapy water, and gently blow. A beautiful bubble emerges from their hand. They can shake it loose and watch it float. If they look carefully they may see water gathering at the bottom of the bubble, making it bottom-heavy, so it sinks.

Now comes the physics without the pain. Water has like a thin skin on the top of it, so the bubble is a bit like a balloon. - that is what surface tension is, in young children's terms. Have they ever seen insects "skating" on the surface of a pond?

There are some wonderful effects you can achieve with the help of lighting, and this is where children can be encouraged to use their eyes carefully. Can you see your own reflection, or the classroom window, or anything else, in the bubble? Does it look exactly like you, or is it distorted because of the round shape?

Can you see any of the colours of the rainbow? This is a complex business to explain, but light is made up of all the colours and the bubble splits it up into separate colours (refraction).

Bubbles are also marvellous for the development of language - "floatsink", "shiny", "reflection", "heavylight", "hover" and many others. For young children even the word "bubble" itself is fun to write, with its three "b"s and silent "e". What about "iridescent"? Later, maybe, but you never know.

Children can finish by drawing or painting a picture of a bubble with their own reflection in it, or one showing the classroom window, or the rainbow colours they saw - put them up on the wall as a bubbles display.

At this early age the physical phenomena of the universe can be incredibly exciting. What a pity that physics is often seen by adolescents and adults as such a dreary and theoretical science!

Ted Wragg is professor of education at Exeter University


* A mixture of ten parts of warm water to one part of concentrated washing-up liquid

* Plastic tubescontainers

* Scissors

* A bowl to hold the water and yogurt pots to make the soapy mixture

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