It's a good thing that Hannah and Bob have such a nice, smart babysitter. When Laura suggests that they make a kite to fly at the beach, the kids immediately start arguing over whether it should be decorated with a lightning bolt or a whale. Laura draws a line down the length of the kite, so they each have exactly the same size and shape to draw on. Later, the children divide the back seat of the car, the beach blanket, and even their sandwiches into two equal parts.

Symmetry is a geometric property that helps children classify shapes.