Arnold Lillis, age 10, of Akron, Ohio, for his question:

WHAT IS THE LIGHTEST WEIGHT WOOD?

Balsa is the lightest wood in commercial use. It comes from the balsa tree.

The lightest kind of balsa wood weighs about three pounds per cubic foot, based on a specimen measured at a volume when air dried, and weighed when oven dried. This is about one third the weight of cork.

Most balsa is light because air fills its cells when the wood is dried out.

The balsa tree has large ivory colored, vase shaped flowers that produce its fruit and seeds. The white to cream colored wood has a silky sheen and feel.

Balsa gets its name from the Spanish word for "raft." It was so named because the people of tropical countries have used the logs for rafts. The balsa grows from southern Mexico to northern Venezuela, and along the western coast of South America as far south as Bolivia.

Worlds largest producer of balsa wood is Ecuador. Costa Rica also turns out lots of the lightweight wood, which is used in model making and some kinds of boats, truck bodies, life rafts and buoys. Balsa wood is also used as an insulating material in incubators and in refrigerator cars and trucks.