Illustrate the cracks in the Earth’s crust with food.
Conduct edible environmental activities with fourth-grade students to inspire their taste for geology. Employ several methods to discuss and illustrate the layers of the Earth’s crust. Adjust the model to illustrate the current area of focus for your students. Food serves as a universal unifier to help teachers engage students in the lesson material.
Boiled Egg Method
Utilize a boiled egg as a simple, low-cost method of illustrating the composition of the Earth. The hard shell of the egg is like the thin, hard crust on top. The large white inside is like the mantle of the Earth; the yolk is the core. Explain the differences between the molten mantle and the solid boiled egg white to the students. Clarify that the Earth has four layers instead of three. Boil the eggs to cut them in half for the students to view the three components. To further illustrate the concept, ask the students to roll the boiled eggs on a desk while gently pressing on them to create cracks in the shell. The resulting cracks will appear much like the plate boundaries in the Earth’s crust.
Edible Earthquake Method
Gather different types of candy to show students how the earth’s crust moves during earthquakes. Explain that different types of rock in the earth’s crust react differently to the movement of the plates on the Earth’s crust that cause earthquakes. Use gum and candy bars to illustrate how plate tectonics produce cracks in the crust in some places but not in others. Hold two opposite ends of a piece of gum. Press them in toward each other to show what happens when the plates on the Earth’s crust collide. Pull the ends of the gum apart to show what happens when the plates separate. Hold opposite ends of the gum, move one end of the gum forward while moving the other backward along the same horizontal plane to show plate sliding movement. Repeat the same activity with a candy bar showing how the rock types–soft or hard–affect the final result of the plate movements.
Gelatin Model Method
Create a layered gelatin dessert topped with graham cracker crumbs to represent the layers of the Earth and the crust. Layer three different gelatin flavors in different colors. The graham crackers represent the crust. Inform the students that the crust is much smaller than any of the other layers of the Earth. Note that the gelatin is cold, but the layers of the Earth are hot inside. The one exception in terms of heat is the crust on which we live.
Sandwich Cookie Subduction
Show students how subduction happens when an oceanic plate of the Earth’s crust is thrust under a continental plate. Pull the two halves of a sandwich cookie apart. Use the side of the cookie that contains the most cream filling. Hold the cookie with the cream filling side up. Insert the cookie into your mouth, sliding your upper teeth over the filling. The cream filling will build up on your teeth. The motion illustrates the concept of subduction.
This experiment works with frosted cookies as well. The student holds the cookie with the frosting side up. The frosting represents sediment on the ocean floor. The student’s teeth are the base of the continental plate. The student scrapes the frosting off the cookie with her teeth, showing how sediments from the ocean end up along the plate boundary, building up coastal land.