Hanging Mobiles
Children can construct a hanging mobile of the solar system using simple supplies. The planets may be represented by different colored balloons or circular pieces of cardboard. Hang the planets where they belong in relation to one another from a heavy gauge wire frame of circles held together by a cross of wire at the center. Suspend a yellow tennis ball in the middle to represent the sun. Paint the balloons or cardboard pieces to represent each planet's characteristics. You can hang the mobile on a pole attached to a table if needed.
Dioramas
Three-dimensional dioramas can be made using cardboard boxes, open to the side, with representations of scenes built inside. One could be built for each planet and all of them arranged on a table in order of distance from the sun. The contents might detail what the surfaces of the planets appear to be. The Mars surface, for example, could be made of crumpled red paper to represent the rocky terrain. The boxes could also be painted black inside with glitter for a night sky full of stars.
Building A Scale Model
The sun and the planets could be constructed to fit calculations of relative size for a scale model. Paper mache could be fashioned over various round objects. A beach ball could be paper mached and painted yellow for the sun. A paper mache basketball may be painted the color of Jupiter and a small rubber ball painted blue and white for Earth. This kind of project will get children thinking about relative concepts of size and scale in concrete ways.
Human Models
A map of the solar system could be created using human planets. Students could stand at relative distances to one another. They might wear clothes with colors of the planets, or just the first letter of the planet and have people in the audience guess the rest of the word. They can give information about their planet, for example, "I am Jupiter, the biggest planet in the solar system."