With church scandals, Internet porn and teenage romance, sex education could be one of the most wide-ranging and important subjects taught in middle and high school, some child psychologists say. Yet for better or worse, most of the nation's sex-ed classes focus on a handful of subjects -- including anatomy, abstinence, AIDS -- and offer little guidance to boys and girls trying to cope with a host of physical and emotional changes.

Though approaches vary from school to school, most start with what some educators call "fifth-grade plumbing," a quick explanation of where babies come from, said Tamara Kreinin, president of the Sexuality Information and Education Council of the United States, a New York-based nonprofit organization that works with schools and parents. In middle school and beyond, Kreinin said, many students get a smattering of courses, some on sexually transmitted diseases, others on the importance of avoiding sex. "Sometimes the course amounts to being shown an hour-long movie, without any discussion afterward," she said.

Many teachers shy away from edgier topics such as sexual abuse, harassment and date rape -- or how, for example, a 13-year-old might handle sexual involvement with someone 10 years older. "Teachers will tell you, 'We wouldn't touch those subjects with a 10-foot pole; the parents would go nuts,'" said Sal Chiariello, who runs an innovative sex and development education program in Rockland County, N.Y., for kindergarten through 12th grade. "There's a lot of apprehension when it comes to this stuff. Teachers are worried about losing tenure, the administrators are afraid of the parents, and parents fear for what their kids might be learning."

In this environment, a discussion of sexuality or relationships with older peers or adults would probably be disastrous, he said. "Even in 12th grade, there are kids with very mature bodies who have no concept of consent ... and believe me, in a large high school with thousands of kids, there are going to be some predators who are watching to see which ones are vulnerable."

For now, administrators say, political debate over whether to teach contraception has precluded many educators from including the topics teenagers most want to learn about -- such as how to manage erotic urges, relationships and pressure to have sex. "Right now, we're having an argument over whether we should even mention condoms in the classroom," said Tina Hoff, vice president at the Kaiser Family Foundation, a nonprofit health research group in Menlo Park, Calif. "We're not even close to a discussion about giving kids skills to negotiate whether or not to have sex."

That's as it should be, millions of parents say: Schools have no place giving advice about sexual behavior, beyond describing the benefits of abstinence. Some policymakers agree. In recent years, the federal government has set aside some $400 million to support programs that teach abstinence until marriage. Nationwide, about 34% of high schools teach abstinence-only curricula, downplaying or omitting discussion of contraception, according to a 1999 Kaiser Foundation survey. Another 58% of schools in the survey reported teaching comprehensive courses, which include discussions of contraception.

When asked what they want their kids to learn in sex education, parents are generally more demanding than teachers. In a 2000 Kaiser survey, more than eight in 10 parents of teenagers nationwide said schools should teach students how to use condoms, as well as other contraceptives, and how to talk about protection with partners. About three-quarters said that sex-ed classes should discuss sexual orientation and abortion. Almost all of the parents surveyed wanted schools to help their kids handle the pressure to have sex, and the emotional consequences of becoming sexually active.

"The parents themselves sure aren't doing it," said Hoff. "So many kids are getting their sex education from other sources, from the media, from the WB network and MTV. I think even network executives would agree those aren't the best sources."

California requires school districts to cover a number of topics related to sex, including contraception and pregnancy. Students typically get two to five weeks of classes, first in the seventh grade, and again in 10th grade, said Ric Loya, of the HIV/AIDS prevention unit of the Los Angeles Unified School District. "These are the highest-attended classes of the year," said Loya. "The kids are just packed in, even if the teacher is boring."

Though most teachers stick closely to the curriculum, Loya said, all get questions from students on everything from how to recognize sexual advances to how to handle their boyfriend's moods. "Sometimes they raise their hand in class, sometimes they'll come up to you afterward, but that's how many things are handled -- informally," he said.