Parents often use toys to demonstrate the wonders of scientific principles.
Balancing toys of a variety of shapes and sizes have been around for centuries, teaching children (and adults) about the laws of physics. The scientific principle illustrated by this simple toy is that you can balance an object on a point if the object's center of gravity is directly below the point of support. In the illustrations below, the center of gravity has been manipulated so that it is no longer within the object itself but at a point in space vertically below it, and so the object seems to balance magically. You can easily make a balance toy with materials found around the house that will fascinate and delight toy-lovers of all ages.

A toolbox balancing toy
( *see image on bottom left of left column )

Materials: a pencil or popsicle stick, one foot of bendable wire, a drill, and an even number of washers, bolts, or other weights.

Directions: Drill a small hole through the pencil or popsicle stick about an inch from the bottom. Thread the wire through the hole and tightly wrap it around the pencil or stick a few times so an equal amount of wire protrudes from each side. Bend the two halves of the wire downward so that they hang several inches below the hole. Form a hook at each end and add an equal amount of weight-washers or bolts-to each. Experiment with how much weight it takes to make the toy balance. Is there a way to make it work if there is a different number of weights on each arm? Once you have balanced the toy, close up the ends of the wire to keep the weights from falling off. Balance the toy on your finger, your nose, or even on the eraser of another pencil.

A dinner party balancing toy
( *see image on bottom right of left column )

Materials:
a wine bottle, a cork, a pin, a quarter, and two forks.

Directions:
Place the pin into one end of the cork so that at least half the pin is sticking out. Insert the forks into the cork as shown in the illustration with the pin head facing down. Put a quarter over the mouth of the bottle and place the pin head in the center. If necessary, adjust the forks until the cork stands upright. Gently give the cork a spin and watch it go!

-Peter Gittleman
Director of Interpretation & Education