In Primary 4 and 5 the children took part in three investigations throughout the week:
The Cornflour Investigation
When you run your fingers through the cornflour, it acts like a liquid. But when you punch it or move your hand quickly though it, it becomes hard and behaves like a solid.
The cornflour particles are suspended in the water, so it flows like a liquid. But when you apply a force to it, the particles lock together, acting like a solid. As soon as the force stops, the slime goes back to being runny.
The Lava Lamp Investigation
Oil floats on the surface because water is heavier than oil. This means that water is denser than the oil. The tablet reacts with the water to make tiny bubbles of carbon dioxide gas. These bubbles attach themselves to the blobs of coloured water and cause them to float to the surface.
Blowing Bubbles
Mixing washing-up liquid with water forms a solution. When you blow a bubble, air is trapped by a thin film of your bubble mixture. This film is made of a layer of water sandwiched between two layers of soap. A bubble pops if the soapy outer skin is broken. This can happen as the water in the bubble evaporates, or if the bubble touches something dry or oily. It can also happen when the bubble becomes too big and there isn’t any more soap to create the sandwich layer. If the bubbles last a really long time, you might see the colours shift as the water drains around the sides of the bubble back onto the flat surface. Eventually, the bubble gets so thin you can barely see it – right before it pops by drying out!
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