Demonstrating Convection (Grades K-3)
Convection in fluids is well-demonstrated with cooking oil, food coloring, a glass beaker, and a Bunsen burner (or candle). Use caution when working with matches, beakers, and hot oil. Secure the beaker one inch above the flame. Fill the beaker half-full with oil. With an eye dropper, place a few drops of food coloring near bottom center of the beaker. Beads of food coloring will rise with the thermal plume in the oil that forms above the candle. The beads will spread laterally near the top of the oil and then sink along the wall of the beaker. Have students describe and explain their observations. How is the model like the Earth? How is it different?
This activity demonstrates convection in fluids. It is important to remind the students that convection in the mantle is in solid rock. The higher temperatures and pressures within the Earth cause the rock to behave in a plastic way, much like toothpaste squeezed through a tube.