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The surface of our planet is a thin layer that is broken up into about six major pieces, called 'plates'. These plates are riding on top of a slowly moving layer of molten rock. Depending on how this molten rock under the Earth moves, continents can be pushed into each other or pulled apart.

Topics and Connections:

• Continental drift
• Scale models

Materials:

• 1 small "Milky Way" candy bar for each student
• plastic spoons

Directions:

Teacher:
Explain that the Earth’s surface is broken up into many pieces that are constantly moving.

Students:

• Rinse off your hands. Use the tips of the plastic spoons to make five or six cracks along and across the top of the Milky Way bar. The cracked pieces of chocolate will represent Earth's crustal plates.
• Hold your candy bar with one end between each thumb and forefinger.
• Slowly stretch the candy bar an inch and watch what happens to the chocolate. (There are parts of the Earth's surface where the plates are moving apart, and new rock rises in between the cracks.)
• Slowly press the bar back together, and keep on pressing for another half inch. Watch the chocolate pieces again. When they hit each other, they may rise up to form mountain ranges, or one "plate" may slide over another. Both of these things are occurring on parts of the Earth.

Questions To Ask:

• If you were tiny enough to ride on one of those pieces of chocolate, what would it feel like when there was a collision? A separation?
• What would you see?

Follow up:

• Get a map of Earth's surface which shows features on the continents and sea floor. Try to figure out where some of Earth's plates are.
• Brainstorm answers to the questions, "How could you actually tell that the plates are moving?", and "How could you measure the speed?"

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