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.
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!