A panel that investigated allegations of racism at South Lakes High School said yesterday the Reston school should attempt to counter the perception that blacks are graded more harshly than whites and are not encouraged to enroll in advanced courses.

Overall, however, the panel said that most of the black parents' allegations it investigated could not be proved, and that "there was no evidence to indicate that the majority of the South Lakes staff exhibit racist behavior."

The nine-member panel, whose members represented the parents, the Reston community, the PTA and the Fairfax County school system, was convened to examine a petition by three dozen black parents last fall complaining of racism in grading, discipline and employment at South Lakes. The school has 300 blacks among its 2,200 students.

The petition touched off a furor in Reston, a community created 25 years ago with the goal of housing a mixture of races and income groups. The petition also came amid a drive by the Fairfax County school system to improve lagging achievement of minority students.

A school system investigation in March into the parents' complaints concluded that there was no overall pattern of discrimination but some cause for concern. When that report was released at a stormy community meeting, the parents demanded an independent investigation.

The independent panel, created by both school and community leaders, reviewed 11 of the 18 allegations by the black parents, saying the other seven already had been dealt with by the school system. It found no basis for nine.

The panel concluded, however, that the school should respond to perceptions by some students and parents that blacks are graded more harshly than whites, which creates a "negative learning environment." It also urged steps to direct more minority students into academic honor societies, national merit programs and classes for gifted students. In an appendix to the report, school officials said they are revising the selection procedures.

The panel said minorities must be aware that not every perceived slight is a racial one, and that school staff should show more sensitivity "to the unique problems of minority groups." It urged more help for low-income students of all races.

"We exonerated the school -- or teachers at least -- in that we could not find blatant discrimination," said James Hayter, a PTA representative on the panel. "On the other hand, sensitivity is something teachers need to be aware of, sensitivity to minority kids."

The school system appendix to the report listed 18 steps the school is taking to meet the concerns of minority parents, including a new program to help low-achieving students, additional meetings to let parents air their concerns, help for students with discipline problems, human relations workshops and vigilance against racist graffiti.

Hayter said the school's most vocal critics would not be satisfied by the report, but most people would agree the school is trying "to get something done there."

Fairfax County School Superintendent Robert R. Spillane, in a statement, said the "spirit reflected in the report augured well for cooperative action" at the school.