This is what teenagers at Bethesda-Chevy Chase High School tell you: They talk about sex.

In the hallways. At lunch tables. Who's doing it. Who's not. Girls talk to their girlfriends. Boys talk to boys. Girls talk with boys who are friends, or their boyfriends.

"People talk about sex all the time," said 16-year-old Claire Davey-Karison. "It's casual [conversation], you know. You'll hear gossip. It's no big deal."

But sex education has become a big deal in some Montgomery County schools -- a deal that involves lawyers, organized parent groups and a federal court. Although students like Claire talk about sex in the same casual manner they might discuss last night's homework or the hijinks of Marissa and Ryan on "The O.C.," some adults are less than comfortable with them learning about it -- or certain aspects of it -- in class.

Last month, Superintendent Jerry D. Weast scrapped revisions to the county's health education curriculum, which for the first time allowed eighth- and 10th-grade teachers to initiate discussions about homosexuality. The revised course materials included a video, to be shown to sophomores, that used a cucumber to demonstrate how to put on a condom.

Weast's decision, which was endorsed by the county school board a few weeks later, came after two groups filed suit and won a temporary injunction barring teachers from offering the program this past spring to students at six campuses, including Bethesda-Chevy Chase.

The groups, Citizens for a Responsible Curriculum and Parents and Friends of Ex-Gays and Gays, argued that the condom video would encourage teenagers to have sex and that allowing teachers to discuss homosexuality might send the wrong message to those confused about their sexual identity.

What's more, the groups said students should also be taught that people can choose not to be gay.

With summer break a few days away, about a dozen students from Bethesda-Chevy Chase High recently offered their take on the sex education debate. The teenagers said they are fortunate because they feel comfortable talking about sex with their parents. They worried about youths who don't have adults they can turn to.

"I know it's a big deal to adults," said Laura Brewer, 15. "Adults fear that if we're learning about it, we'll be more influenced to carry it out. But not teaching it isn't the way, because one day kids are going to have sex, and they're going to need to know how to protect themselves."

Laura and the other students said they realize that some of their peers hold different views, that not everyone talks about sex in hallways and lunchrooms, and that some adults prefer to keep discussions about sex within the family. Still, they said, it's important for parents to understand that teenagers these days are bombarded with sexual images.

"People act like they're dropping some bombshell on us," said Brandon Corbin, 16.

Brandon, who will be a junior in the fall, said many teenagers know what condoms are (and some have known since elementary school because of older siblings or classmates). They know people who are gay, might have friends who are gay and, even if they aren't themselves, have classmates who are sexually active.

"I know [parents] don't want to believe their kids are having sex," said Rebecca Hughes, 16, who will be a senior in the fall. "But it's out there."

The statistics speak for themselves: By the time they have reached their senior year in high school, three out of five young people in the United States have had sex, and one in five of those has had sex with four or more partners, according to the 2001 Centers for Disease Control and Prevention's Youth Risk Behavior Surveillance.

"You can take the sex out of the curriculum, but it's still going to be in society," said Laura, who just finished her sophomore year and would have been in the class introduced to the contested sex-ed curriculum.

A study by the Kaiser Family Foundation on the media habits of young people found that on average, 8- to 18-year-olds watch nearly four hours of television a day and devote nearly two hours a day to listening to music. Another Kaiser report released two years ago said that in a sampling of programming from the 2001-02 television season, 64 percent of the shows included some sexual content, 32 percent had sexual behavior and 14 percent featured strong suggestions of sexual intercourse.

In the top 20 shows watched by teenagers, including "Friends," "The Simpsons" and "That '70s Show," 83 percent included some sexual content, the study found.

Although shows favored by teenagers were more likely to include sexual content, the researchers found that the programs also were more likely to include a reference to safer-sex issues, such as waiting to have sex, using protection or the consequences of sex.

With so many images of sex on television, in movies and in song lyrics, the Bethesda-Chevy Chase students said, parents shouldn't be shocked that teenagers are curious. And Mark Strom, 16, said adults don't understand something else: In the end, sex education isn't all that exciting.

It's a class, he said. It's a grade.

"People think this stuff is more advanced and racy than it really is," he said. "That's just not true."

Bethesda-Chevy Chase High School students Chris Buck, Courtney Williams and Jordan Hardy sit in front during a discussion about the sex education debate in Montgomery County. Parents "don't want to believe their kids are having sex. But it's out there," one student said.