Students conduct a hands-on experiment designed to demonstrate how continents and oceans formed and why the manner of formation is relevant to a study of volcanoes.
Objectives
Students explore theories of how the continents and oceans formed (Pangaea and continental drift). Students conduct a hands-on science experiment and record their observations. Students draw logical conclusions based on scientific principles.
Background Information
Earth's interior consists of four shells: a thin, brittle crust; a thick mantle that is brittle near the top and more plastic at the depth; and two layers of thick, metallic core. Most Earth scientists believe that the temperature within Earth increases with depth. The lower part of the mantle is hotter and therefore less dense than it is near the top. Because of this, convection cells develop in which hotter, less-dense mantle material sinks. Near the top of the mantle, the convection cells move parallel to the surface, carrying the more brittle crustal (lithospheric) plates with them. In some places, the plates move away from each other (divergent boundaries), and in other places, they move toward each other (convergent boundaries). In some places, they move past each other. The boundary between the two plates is called a tranform fault. The lithosphere (crust) is made up of plates. The plates are large sections of crust and upper mantle. The plates, carrying both oceanic and continental rock, float on the hot upper mantle. The plates come together, separate, and slide past each other, creating regions of volcanic activity, mountain building, and earthquakes.
Procedure
Fill the container three-quarters full with water, center it on the heat source, and heat until the water simmers, but do not let it boil. Gradually pour oatmeal into the water. (CAUTION: Allow oatmeal to simmer, not boil. Boiling oatmeal can splatter and burn.) Add 1 drop of food coloring to four different areas near the center of the oatmeal. Have students observe the movement of the food coloring and sketch the movement on a lab sheet, using arrows to indicate the paths of food coloring. Sprinkle irregularly broken pieces of graham crackers or wood chips on top of the simmering oatmeal and have students observe and sketch the movement of the pieces, using arrows to indicate their paths.
Discussion
Ask students: What causes the oatmeal to rise and sink or to move sideways? What causes the graham crackers (wood chips) to move? In what direction(s) did the pieces move when they were directly over the rising oatmeal? What do the oatmeal, graham crackers, and the heat source represent in an actual convection cell?
Assessment
Evaluate students on their sketches and their responses to the discussion questions.
