Joan Groom, age 10, of Tekoa, Wash., for her question:

HOW IS FOAM RUBBER MADE?

Most of the natural rubber used today is obtained from the para rubber tree. A milky fluid is obtained from the tree and processed into thousands of different rubber items.

For more than 100 years, the United States has used more than half of the world's supply. Akron, Ohio, is theleading manufacturing center.

Foam rubber, one of the most popular items, is made by beating air into the rubber before it is poured into vulcanizing molds. Sponge rubber, which is similar, is prepared by the addition to ordinary rubber of a powder that forms a gas during vulcanization..

In 1770 Joseph Priestly discovered the bouncy product could be used as an eraser and from this came its name: rubber.