The inside of Earth is an area unable to be viewed directly by humans and is only measured or known about by indirect measurements. Using the measurements provided by scientists and their interpreted knowledge of the Earth's core and scaling them down so that 1 inch represents 500 miles, it is possible to create a 16-inch, 3-D model of the Earth and its layers to gain a better understanding of what is going on beneath our feet.

### Items you will need

- 16-inch foam ball
- Pencil
- Measuring tape or compass
- Markers or acrylic paint

Cut the foam ball in half, and then mark the center of the ball with a pencil or by pushing a thumbtack into the spot.

Measure 1.5 inches, or 3.81 cm, from the center and draw a circle to represent the inner core. Use a marker or acrylic paint to color the inside of the circle bright yellow.

Measure 4.3 inches, or 10.92 cm, from the center and draw a circle representing the outer core. Use a marker or acrylic paint to color the inside of this circle orange.

Measure 7.87 inches, or 19.98 centimeters, from the center and draw a circle representing the mantle. Use a marker or acrylic paint to color the inside of this circle red.

Color the area left outside of the circles brown, representing the crust. Draw continents on the outside of the sphere and color them green, and then color the remaining areas blue to represent the oceans.

#### Tips & Warnings

- Cutting out only a one-quarter or triangular quadrant of the ball will provide a more-spherical and appealing end product, but is more difficult and requires measurements to be made multiple times.
- This model is created with a scale of 1 inch equal to 500 miles. Multiply the number of inches in each step by 500, and then divide the answer by the scale you prefer if you want to change the size. For example, to create an 8-inch model, make each inch twice as large. Multiply each measurement by 500 to obtain the true size, and divide this number by 1,000 to find the number of inches to use in your new scaled size.

#### References

#### Photo Credits

- Chad Baker/Digital Vision/Getty Images