Christy Fredregill, age 13, of Casey, Iowa, for her question:

WHAT CAUSES A CHILD TO BE HYPERACTIVE?

A hyperactive child has a disorder that causes him to be almost completely active. From 1 percent to 5 percent of the elementary school children in the United States suffer from hyperactivity, or, as doctors call it, hyperkinesis.

Hyperkinesis is believed to result from a physical disorder, such as a problem in the brain. It may also result from social and physical difficulties. Many hyperactive children become calmer as they grow older. Most children with the problem are boys.

Some doctors treat hyperkinesis with stimulant drugs, such as amphetamines. These drugs tend to calm from half to two thirds of the children treated. Some schools also employ special teaching methods to help hyperactive children increase their ability to concentrate.