Mixing and making
Chemistry · Early Years · The School
Stirring things into water
Stir sugar into warm water and it disappears — it has DISSOLVED. Stir sand into water and it just sits at the bottom. Try salt, flour, and a little cooking oil, and say what each one does before you stir.
Coming apart again
Leave the sandy water still and the sand settles, so you can pour the water off. The sugar water looks clear, but the sugar is still there — taste a drop and you will find it. Some mixtures come apart easily and some do not.
Changes that stay
Some mixing makes something new that will not come apart. Mix flour, water and heat and you get a cake; you cannot get the flour back out. Baking is chemistry, and the kitchen is where most children meet it first.
Stir a spoon of sand into a cup of water: cloudy, and it looks permanent. Leave it ten minutes and the sand settles at the bottom; pour it through a coffee filter and the sand stays behind. Now stir a spoon of sugar into another cup: it disappears completely, and no filter will get it back — but leave the cup on a warm windowsill for two days and the sugar reappears as the water goes. Two mixtures, two different ways back.