G1-The Wind 500 – 600L_03

It seems like a beautiful day.
You notice the trees in the yard are swaying back and forth.
The trees do not sway back and forth every day.
Some days they are very still and do not move at all.
You notice a nearby flag and see that it too is waving.
You see some kids down the street flying a kite.
What do all these things have in common?
They are all caused by moving air.