Lori Jones, age 10, of St. Catharines, Ontario, Canada, for her question:

What is rubber made from?

The first rubber balls in the world were bounced by Indian children of South America. Their parents made rubber water bags and used rubber to waterproof their feet. The Spanish explorers were told that the stretchy, bouncy, waterproof material came from the cahuchu    meaning the weeping tree. We call it the rubber tree. When its bark is stripped, it weeps liquid tears of sap called latex. And this latex is the main ingredient in natural rubber.

Nowadays, however, we use more synthetic rubber than natural rubber. The synthetic rubber, of course, is man made from simple chemicals. One of the most useful recipes is called SBR    short for styrene butadiene rubber. The styrene is a liquid chemical taken from coal tar. The butadiene is a liquid gas taken from petroleum. Both ingredients are left behind when oil from the ground is changed into gasoline.