water shrinks
Fill a jar to the top with water and place it in the freezer
for about 30 minutes. If necessary add a few drops of water
after placing the jar to fill the jar exactly to its top.
The water level goes down as the water cools. If warm water is
put into a narrow mouth bottle the level may drop 1/2 inch.
Another way to do this experiment is to put hot water into
a soda bottle and leave it cool as it sits on a counter or
tabletop.
As the water cools movement of the water molecules becomes
less. Less movement allows the molecules to move closer
together because they do not bounce off each other as much.
Since the molecules are closer together the water takes up
less space.