The 6-year-old appeared to be the classic bad boy of his Fairfax County classroom. He talked out of turn, tipped over chairs and tore up other children's papers. When his classmates ignored him, he threw temper tantrums and sometimes started fights.

Finally, after months of disruptions, the boy's teacher took strong action. She built a four-foot square, five-foot high cardboard enclosure, open at the top. Then she moved his desk inside and told him to stay there unless he had permission to come out for class instruction or discussions. Some days he didn't want to come out at all.

His first-grade classmates took to tossing grass into the isolated study area "to feed the animal in the box," the boy's mother and others said. The youngster, increasingly depressed, began to avoid the other children, preferring the solitude of his womblike fortress.

There was a catch: The boy was not simply a classroom cut-up. He has been diagnosed as suffering from hyperactivity, a behavioral disorder whose symptons resemble the acts of an intentionally unruly child. The boy, who is under a psychiatrist's care, shares the disorder with an estimated 5 million other elementary schhool-age children.

Fairfax school officials last week defended the box technique, saying it helps the hyperactive child concentrate by blocking out distractions.

Although the boy's parents, Peggy and William Robbins of Reston, said they were aware that their son was being kept away from other students, they said they see his "box treatment" as a cruel form of punishment inflicted on a child for a handicap he could not control.

The boy had spent five months in special confinement. When the Robbinses learned of his treatment late last month, they took him out of the school.

"I thought [isolation] meant putting him at the back of the room out of hands' reach or whisper reach" said Peggy Robbins, "I never comprehended that he had a box he was living in."

The Robbinses found out about the enclosure when their son came home one day and complained that another student had kicked his box. He apparently had been too embarrassed to mention the box earlier, his mother said.

"The teacher didn't know how to handle Richard, so she would rather just stick him in a box at the back of the room and forget about him," Peggy Robbins said. "They just can't do that. If they did it to my son, they could do it to anybody."

The boy's plight is an example, officials say, of what can happen when school systems find themselves under pressure to teach children with learning disabilities in the same classroom with so-called normal students. Particularly hard-hit, they say, are hyperactive children whose aggressive behavior often leads to punishment -- not treatment.

While the principal at the boy's Reston elementary school, Forest Edge, insists that the isolation technique is helpful, some parents say it impedes their children's ability to control themselves and develop socially.

"How does a child [in a box] learn to deal with the overload of their senses that they constantly face?" asks Jamie Ruppmann, president of the Fairfax Association for Children with Learning Disabilities, who recently fought a county decision to isolate her hyperactive child. "Does this mean that the only way to get a child to learn is to throw him in a white tiled bathroom? Kids can't stay on drugs or in boxes forever."

Although officials estimate that hyperactive youngsters make up between 4-to-10 percent of American elementary school students, they have not yet determined either a cause or a cure for the disorder. Some doctors say it is a physiological problem, while others view it as purely psychological. Some favor treating it with drugs, but others oppose drug therapy.

Practically all that can be agreed upon are the symptons that hyperactive children display. They easily are distracted, rushing from one task to another without finishing anything. They are impulsive and excitable, and demand endless attention from everyone around them.

Often these children can be disruptive, throwing temper tantrums for no reason, or they are aggressive in their dealings with other children. Constantly in motion from early morning until late at night, they often are poorly coordinated and immature for their age. The majority of them are boys, and many have other learning disabilities as well.

According to Forest Edge principal Sue L. Williamson, the box technique is common at the school and is used on approximately two or three hyperactive children there each year. "This is a very accepted practice," she says. "It lets the student sit down and concentrate on his own work."

Williamson acknowledges, however, that the Robbinses' son should have been instructed to view his study area as an opportunity for learning -- not a punishment. "The unfortunate part of this was that the (boy's) teacher (Sally Orlins) never called it a study carrel. She called it a box."

Orlins declined to discuss the case with a reporter.

Federal law requires that the educational program of each handicapped child in a public school be formulated as an agreement between the school and the child's parents, and it is the lack of such an agreement that is perhaps most disturbing to Peggy Robins.

Approximately $19 million in federal funds goes annually toward preparing classroom teachers to teach the handicapped. Federal officials admit, however there is still a long way to go to help all the teachers affected when Congress, in 1976, ordered that public schools make every effort to educate handicapped students alongside their nonhandicapped peers.

Among the techniques advocated for teaching the hyperactive child, according to William Peterson of the Department of Education's Office of Special Education, are smaller class sizes, occasional supervised isolation periods, reduced class hours, frequent consultations with parents, and the removal of the hyperactive child from the classroom to another area by a teaching professional if the child becomes too agitated.

"I would hesitate to advocate such (putting a hyperactive child in a box) unless there was no other alternative," Peterson said. "He's a social being. uAbsolute isolation sounds like a somewhat extreme measure."