RICHMOND, FEB. 8 -- Sex education courses in Northern Virginia public schools were portrayed today as both good and bad examples of what will occur if the General Assembly requires that all school districts in the state adopt a comprehensive family life curriculum.

Several hundred people packed a Senate-House hearing on seven bills offering alternatives to a plan --

proposed by the state Board of Education and endorsed by Gov. Gerald L. Baliles -- that would mandate family life classes beginning in kindergarten.

The hearing highlighted a day in which legislators wrestled with some of the more than two dozen bills that address such emotional issues as teen-age pregnancy and AIDS.

Lynne Mercer of Fairfax City, an opponent of the family life curriculum proposal, said she sat in on a junior high sex education class (she declined to identify the school) in which sex was portrayed as "a fun thing to do if you are mature enough to handle it."

"The teacher told the girls that if there was a shiny ring on the outside of a boy's wallet it meant he was not using a condom," she said.

Also, Mercer said that the eighth grade boys "squirmed" in their seats when they were taught about masturbation.

Another opponent of the curriculum proposal, Walt Barbee of Lorton, handed committee members charts that he said showed that school districts with comprehensive family life programs -- including Falls Church, Alexandria and Arlington -- have higher rates of teen-age pregnancy than those that do not teach sex education in detail, and that the rates continue to rise for the former group while they are declining for the latter.

Mary Lee Tatum, who teaches sex education in Falls Church, responded that the rates reflect urban conditions, not the pros and cons of sex education.

"Our culture essentially treats sex as pornographic," she said. The classroom is "one of the few places where kids can talk safely and sanely about sex, including how to say no."

Tatum, whose classes have been criticized by opponents of the legislation as examples of explicit, amoral teaching, said she has never had a complaint from a parent in 14 years of teaching in Falls Church. "Not one," she said, "despite great efforts to organize {opposition} from outside."

The Rev. Rob Vaughn, former pastor of the Beverley Hills Community United Methodist Church of Alexandria, said he "saw beautiful results" when that city's sex education program, considered a national model, was instituted in the early 1980s.

Vaughn, now a pastor here, was hissed when he urged the legislators to reject the alternative proposals, specifically one that would prohibit teaching about homosexuality as anything other than "deviant, dangerous and illegal."

Most opponents agreed that schools should teach about sex and family values -- about one-third of the state's 139 school districts have no such classes -- but they argued in favor of giving local schools more say in deciding the content and timing of teaching those subjects.

S. John Davis, state superintendent of public instruction, who helped develop the family life curriculum in Fairfax County when he was superintendent there, said he originally was unenthusiastic about a state-mandated program "because I knew what we were in for" from opponents.

But the proposed curriculum, he said, while mandating action, "permits flexibility."

On another subject, the first two of about 20 bills concerning AIDS reached the Senate floor today for votes. Each passed.

One is designed to allow rescue squad workers to know when they have come into contact with victims of AIDS or other infectious diseases; the other would permit physicians to notify the state health department about any patient who has testified positive for exposure to the acquired immune deficiency syndrome virus.

A House subcommittee on health, chaired by Del. Warren G. Stambaugh (D-Arlington), considered bills proposing seemingly everything from a plan by Del. Robert K. Cunningham (R-Springfield), which would test everyone age 5 and older for AIDS exposure, to a measure that would require hospitals to alert morticians when people with AIDS die.

A proposal by Del. David G. Brickley (D-Prince William) to require AIDS tests for those convicted of prostitution or intravenous drug use won subcommittee approval, over Stambaugh's objection.