A Fairfax County Circuit Court judge sentenced a 13-year-old youth yesterday to probation for the rest of his years in the school system after a jury found him guilty of assaulting a teacher after she smacked him.

"You were wrong," Judge Richard J. Jamborsky told the student during sentencing. "Basically, this thing got started because you acted like a brat. We're not going to let kids hit teachers and get away with it."

Jamborsky also sentenced the 13-year-old to 100 hours of community service and committed him to the state Department of Welfare and Institutions but suspended the commitment pending good behavior.

The sentencing came several hours after a Circuit Court jury upheld a ruling of not innocent made in August by a Juvenile and Domestic Relations District Court judge. The jury's guilty verdict affirmed that finding after the youth's family had appealed. The juvenile judge had placed the student on 12 months' probation and did not impose a suspended commitment.

Jamborsky did not accept the defense arguments that the youth, who is black, was defending himself after the teacher, who is white, hit him or that racism played a role.

Judge Jamborsky admitted reporters to the trial on the condition that they not identify the youth because he is a juvenile. He has since transferred to another school in the Fairfax County system.

Assistant Commonwealth's Attorney Elizabeth Luttig said the youth, who is 5 feet, 11 inches tall and weighs 165 pounds, "brutally assaulted" teacher Stephanie Weddle, who is 5 feet, 2 inches tall and weighs 110 pounds.

According to court testimony, Weddle, a teacher at Walt Whitman Intermediate School, told the youth and a friend to go to the end of a school line after she saw them cut into the line.

A oral confrontation with the 13-year-old followed and the teacher tried to determine the youth's name. As she was pointing him out to another teacher, the student approached her, coming within inches of her face and telling her to stop pointing at him. He brushed her hand away, and she "smacked" him, she testified.

"I was terrified, he just kept coming," Weddle testified. The student then struck her, knocking her unconscious and fracturing some bones in her face and causing other injuries, she testified.

Weddle was later disciplined for violating school policy by slapping the student. Said Weddle during the two-day trial: "I was stunned that I had even smacked a student. I had never done anything like that before."