In outer space, where there is no air,
astronauts have to wear pressurized space suits
that push against their bodies with the same forces
as the air on earth.
Without air we could not live.
We cannot see it or smell it, but we
can feel it when it moves. Just like water, air
has many uses.
Sailing boats have large sails which
catch the wind to push them through the water.
Windmills harness the power of the wind
to grind wheat into flour or make electricity.