Fold a piece of paper in half and draw half a butterfly on one side. Cut out your butterfly, so that it is symmetric. Trace the butterfly onto a piece of cardboard.
After you cut out the butterfly try to balance it on the eraser side of a pencil. The butterfly’s center of gravity is the point where it can balance on the pencil. Next, tape one or two pennies onto each of the wings near the top.
Find the center of gravity again using the pencil. How did the weight change the center of gravity?