Draw an enlarged ruler on the chalkboard and show students which graduations represent millimeters. Students will each be given a copy of Sizes of Planets Table, which shows the length of each planet's diameter. The diameter is a line that goes from one side of a planet to the other side through its center. Additionally, the table also shows the sizes for scale models of the planets. Ask students to look at the pictures in this activity to help you choose the right color clay for your scale model.
Students make the ball of clay with the right diameter for each planet.
If your planet has rings, cut out the cardboard to make rings. Furthermore, you will need to make the hole in the cardboard a little smaller than your model so that the rings will stick to the scale model. Ask students to put the models in the order shown on the Size of Planets Table. Explain to the students to compare the sizes of the planets, but not the distances between planets. The distances are much greater.