Cut out the shape from a piece of cardboard. Pin the shape to a bulletin board with yarn and attach a weight at the end of the yarn. Draw a line behind the yarn, pin the shape at several different points and draw a line each Time. The point at which the lines cross is the center of gravity of your shape. The teacher will put the definition on the board.
Gravity is the force that pulls objects back toward the earth.
Gravity is the pulling force between two objects due to their masses. The teacher will cut a 1-inch thick slice from the center of a potato. Push the pencil through the center of the potato. Place the capped bottle on a desk. Stick the two forks into opposite sides of the potato.