Lava Lamps and Convection

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Objective: To show and compare the thermal expansion and convection in a lava lamp to the mantle and plate tectonics.

Materials needed:

· lava lamps

· outlet (extension cords might be needed)

Demonstration:

Plug lava lamps into outlet and place on a table in the front of the room at the beginning of class. It helps to turn the lava lamps on for a while before class to give them time to heat up (be careful not to shake the lava lamps once the wax has melted). As the lecture (presumably about convection in the mantle) moves along, the lava lamps will continue to heat up and the wax inside will expand and float up and down in blobs as they change temperature. This nicely demonstrates how convection works and can be tied into the lecture on convection in the mantle. Optionally, you can have the students make observations and comparisons about blobs of different sizes (their speed, shape, internal convection, etc.)

Illustrated are two lava lamps against a geology textbook opened to a section on convection in the mantle.