Make a model to explain the Earth's multiple layers to students or to judges at your sixth-grade science fair. Sixth graders are often required to exhibit their understanding of the construction of the Earth's different layers, representing them through a model design. A plastic foam ball (like Styrofoam) works well for assembling a model of the Earth's various layers, for it already shares the planet's shape and can be modified and designed with colored markers to show the atmosphere, crust, mantle and outer and inner cores. A model of the Earth's layers can be made in less than an hour.
Cut the 6-inch plastic foam ball completely in half with a knife. This allows you to use the sliced area of a half to represent the interior layers of the Earth. Discard the second half of the ball or save it to use for another project.
Draw the Earth's atmospheric layer with a blue marker. The atmospheric layer is to be drawn at the very outer edge of the sliced half of the ball and should be about one-quarter inch in depth.
Draw the Earth's crust. Color around the circumference of the foam ball, on the inner side of the atmospheric layer, with either a dark brown, black or gray marker. The crust is a very thin layer in comparison to the others, so draw the layer about one-eighth inch in depth.
Draw the Earth's inner and outer cores. Color a 1-inch circle at the center of the foam ball with a bright yellow marker to represent the inner core. Color a one-quarter-inch orange ring around the inner core to represent the outer core.
Color the rest of the sliced half of the plastic foam ball with a brown marker to represent the molten layer. Decorate the round portion of the foam ball section to represent the Earth's land and water mass.
Cut five small rectangles out of paper with a pair of scissors, then write a layer name on each. Stick the straight pins through each layer's name tag and then into the layer represented by the model.