Surface of the Earth

The surface of the Earth is always changing. As huge pieces of the Earth’s surface called tectonic plates shift and slide on each other, huge mountain ranges are created. But they never stay huge because of a process called erosion. Given enough time, entire mountains get washed away!
Wind blowing, people hiking, and even rain falling all makes little bits of mountains and rocks chip and break off. One of the most powerful forces of erosion comes from plain old cold water.
Materials:

A baby food jar with a lid 

A Mason jar (big enough to put the baby food jar inside) with a lid
(Make sure it’s OK if you throw these out after the experiment is over.)
Fill the baby food jar with water. Try to fill it so that when you put the lid on, there’s no air in the jar at all—just water.

Put the small jar UPSIDE-DOWN inside the big jar. Put the lid on the big jar, and then freeze your experiment overnight.

Wait until the morning to look inside. Tell everyone not to worry if they hear loud noises coming from the freezer. No peeking!

Cool! The baby food jar will shatter. That’s because water expands and takes up more room when it turns into ice. Since you didn’t leave any extra room in the little jar, the water was forced to press against the glass and it exploded.
Be sure to throw away your experiment without opening the Mason jar, so you can’t accidentally cut yourself on broken glass.
The same thing happens to erode the earth. Rain falls in small cracks in rocks. If it’s cold enough, the rain can freeze and ice can push against the rock, just like the ice pushing against the jar in your experiment. The crack gets bigger and the same thing happens again. Ice chips away at mountains, breaking huge boulders into little pebbles.

Nye Labs, http://nyelabs.kcts.org/homedemos/demo21.html