Compressing Air under Water
You will need: Rubber tube, jar, bowl of water.
When Scuba divers descend into the depths of the ocean they carry their own air with them so that they can breathe below the surface. The tank isn't large, because it is possible to press a large amount of air into a comparatively small container.
You can make your own container of compressed air under water.
Place a jar in a bowl of water and allow it to fill before standing it upside down with the end of a rubber tube trapped inside it.
Blow into the tube and you will see the water level fall inside the jar as you force air into it. Release the end of the tube and you will hear the hiss of escaping air. You will also notice the water rise again in the jar.
It takes a lot of air to move a little water
because the air is compressed in the closed space.
Children learn best through doing
Before children can understand a thing, they need experience: seeing, touching, hearing, tasting, smelling; choosing, arranging, putting things together, taking things apart. Experimenting with real things.
Old-time school teaching used only words and the teachers thought children knew something if they could repeat it. Now we know better. To reach practical understanding we do not need to use many words with young children.
Children are clever. They learn a lot, without being taught. The greatest skill - to be able to talk, to communicate is learnt outside school. In the classroom it's the children who need to talk the most. Unfortunately it is the teacher who does most of the talking!
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