Roll red modeling clay into a ball that measures 1.2 centimeters in diameter, using the metric ruler to ensure it is the correct size. The red clay ball represent the earth's inner core. Create a ball of orange modeling clay with a 3 centimeter diameter. Flatten it into a circle and surround the red "inner core" with the orange "outer core."
Build a 6-centimeter ball of tan modeling clay to represent the earth's mantle. Flatten it into a circle. Surround the orange "outer core" with the tan "mantle." To make the earth's "crust," flatten a piece of blue modeling clay, and wrap it around the tan "mantle," making it as thin as you can.
Flatten some green modeling clay to make the basic shapes of the continents, and lay them on top of the blue "water." Cut a slice out of the upper half of the "Earth" or cut the Earth in half to see the inner layers.
Compare the depth of the crust made of blue and green modeling clay on your model. The layer of the earth that you are standing on is the crust, and compared to the other layers of the earth, it is very thin. Under the oceans, the depth of the crust is about five kilometers. Under the continents, its depth averages 30 kilometers, and under large mountain ranges it can reach 100 kilometers deep.
Locate the tan layer on the modeling clay "Earth." This represents the mantle, a thick layer of hot, semi-solid rock that lies beneath the crust. The mantle is about 2,900 kilometers deep. Pressure causes the mantle to be hotter and denser than the crust. The deeper below the crust, the more the pressure and temperature increases.
Examine the last two layers made of orange and red. The earth's core lies at the center of our planet and is made of two layers, the outer core and the inner core. The outer core layer, represented by the orange modeling clay on the model, is liquid iron and very thick, about 2,200 kilometers.
Locate the inner core of red modeling clay. Earth's inner core is solid iron and 1.250 kilometers in diameter. The magnetic field of the earth is created as the inner core spins with earth's rotation inside the liquid outer core. Scientists now believe the inner core may be composed of two layers.