Just How DO Those Plates Move?

Purpose: To learn how convection currents occur and how they are used to explain
the movement of the Earth’s plates

Materials

• clear glass baking dish
• hot water
• ice cubes
• small plastic sandwich bag
• twist tie
• masking tape
• 2 eyedroppers
• red and blue food coloring
• paper circles from hole-punch
• science journal

Procedure

Teacher Note: This experiment requires hot water, which requires adult supervision. An immersion heater from an aquarium may also be used to heat the water as the experiment is conducted.

1. Fill the glass dish almost completely full of hot water.
2. Put five ice cubes in the plastic bag and close it with a twist tie.
3. Place the bag with ice in the water at one end of the dish and tape it in place. See diagram 1.
4. Place a few of the paper circles on top of the water at the opposite end from the ice and observe. Record observations in your science journal.
5. Using an eyedropper, carefully place several drops of red food coloring on the bottom of the dish opposite the ice cubes. Observe and record what happens.
6. Use the second eyedropper and place several drops of blue food coloring just below the surface of the water near the ice cubes. Observe and record what happens.
7. In your science journal, make a drawing of what you observed with the paper circles and the red and blue food coloring.

Conclusion

1. Describe what occurred to the paper circles when placed in the water? What do you think caused this to happen?
2. What happened to the red food coloring when it was added to the warm end of the water?
3. What happened to the blue food coloring when it was added to the water near the ice?
4. Based on your observations of the activity, how would you describe the theory of convection currents and its affects on plate movement