Air Presses in all Directions
You will need: A jar, balloon.
When we speak about air
pressure, we are often mistaken in thinking that it presses in only one
direction at a time. This, of course, is not so. Air exerts its force in all
directions. Only when a vacuum or an area of low pressure is created does air
appear to marshal its forces and move in the direction necessary to increase
the pressure in that area.
A simple experiment will prove the point.
Take an ordinary rubber balloon and hold it so
that it hangs partially in an empty jar.
blow into the balloon and inflate it, that part of the balloon which is trapped
in the jar swells out until it touches the glass sides. A few more puffs, and
it becomes an easy matter to lift the jar with the aid of the balloon.
The air pressure inside the
balloon exerts its force in all directions, pressing the walls of the balloon
so tightly against the glass jar that it cannot easily be pulled free unless
some air is released from the balloon.
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!