More than 500 Alexandria teenagers representing virtually every ethnic group gathered yesterday morning to talk candidly about race, but for a while, the moderator thought they were painting too pretty a picture.

Jack Moline, a rabbi from the city's Agudas Achim Congregation, asked, "When you go to lunch, how many of you go with someone different?" More than a hundred hands shot up. He frowned theatrically. "You lie like a rug!" he said.

The students from Alexandria's four public secondary schools--T.C. Williams, Minnie Howard, Hammond and George Washington--and three private high schools--Episcopal, Bishop Ireton and St. Stephens-St. Agnes--filled the center of Episcopal's cavernous field house as part of a continuing effort by city officials to explore the sensitive issues of race and culture.

The 90-minute discussion was often as lively and diverse as the participants, with the students examining ethnic stereotypes, hurtful language and the different perceptions of private and public schools.

Moline, dashing about with a hand-held microphone like a television talk show host, eventually succeeded in stimulating debate over choice of lunch companions.

Will Collier, a senior at Episcopal, said that there weren't many other black students at his school and that they had developed a family feeling that made it natural for them to eat together. "We get together because that is all we got," he said.

Doug Rhoades, a senior at T.C. Williams High School, objected. "You make it sound like white people are out to get you," he said. "We are not out to get you."

Justin Harris, a T.C. Williams junior who is African American, said Rhoades had missed the point. "You want to be with people who can relate to your music, to the way you act, the way you talk."

Collier tried to explain it another way. Like most Episcopal students, he said, he lives at the school and cannot go home to his family each night. "You go home to white people each night, right?" he said to Rhoades. "When I am going to be with these people, I am going home."

The comments by students, many of whom were selected by teachers, were mostly upbeat and friendly, and the issues seemed to provoke great interest. By the end of the forum, several students were still lined up to speak when an ear-splitting rock band brought in for entertainment marked the end of the session.

The Alexandria City Council voted in February 1998 to begin a citywide discussion of ethnic issues as part of President Clinton's call for a national dialogue on race and diversity. The sessions held so far among adults have helped "dispel certain false perceptions of the public schools," showing that they are as safe and high-performing as other schools in the area, said Claire M. Eberwein, the vice chairman of the city School Board.

More than 200 of the students at yesterday's forum were from T.C. Williams, whose student body is 45 percent black, 27 percent non-Hispanic white, 20 percent Hispanic and 8 percent "other." During Principal John Porter's 16-year tenure, the school has achieved a reputation for racial harmony and high achievement.

Most students said they expected improvement in race relations. Several cited courses and activities at their schools, such as the Cultural Coalition Club at T.C. Williams, designed to break down ethnic barriers.

"Stand up and look around," said Sandra Hart, a sophomore at T.C. Williams. "What we have around us is a rainbow, and it is beautiful."

CAPTION: Alex Norwood, left, shakes hands with Terry Gaymon under the watch of Rabbi Jack Moline, who led the forum on race and cultural understanding.