G1-The Wind 400 – 500L_03

It is a beautiful day.
You see the trees are moving.
They are swaying back and forth.
The trees do not sway back and forth every day.
Some days, they do not move at all.
You see a flag. It too is waving.
You see some kids flying a kite.
What do all these things have in common?
They are all caused by moving air.