They know which movie theaters routinely check for age -- and which ones don't.

They know that, being a year or two shy of the requisite 17, it's easier to get into an R-rated movie if they're part of a group -- and the bigger the group the better.

And being teenagers, they have decidedly mixed opinions on whether much will be accomplished by theater owners' decision to require photo identification for youths in line to see movies such as "The Matrix" or "Wild Things."

"The more regulation, the more kids will try to get around it," one 15-year-old said.

The owners' announcement yesterday, prodded by President Clinton's attack last week on the violent images put forth by the entertainment industry, is hardly a crackdown on the decades-old movie rating system. Patrons wanting to see an R-rated movie already were supposed to be at least 17 or accompanied by a parent or guardian, but scrutiny at the box office frequently has been lax to nonexistent.

Or, as one 16-year-old from Rockville explained, "you go up and they ask for an ID and you say you don't have an ID." As often as not, that is that and you pay your money and walk on in.

The Rockville teenager sees R movies -- two recent flicks were "Varsity Blues" and "The Matrix" -- and while his parents don't always know beforehand, he doesn't think they care as long as the films aren't "explicit R," meaning loaded with sex.

Waiting before a workout yesterday at the Rockville Municipal Swim Center, he nodded as a teammate talked about how much of what is in R movies permeates daily life. "Everyone is always talking about how to protect a kid's mind, to not expose them," the 16-year-old said in agreement. "Teenagers always get around it."

Like the time one boy showed up with nine other underage teenagers to see "There's Something About Mary." The ticket seller asked the pertinent question but didn't hold the line. "We all admitted we weren't old enough," recounted the boy, now 15. They were let in with a warning: "Don't do anything bad or we'll have to kick you out."

As for Amy Rocap, a 16-year-old from Vienna, she has been getting into R-rated films with little difficulty since she was 13.

Most places, she said, don't ask for proof of age. At those that do, she has older friends buy tickets for her or she waits to rent a restricted movie at the video store. With some people using fake IDs to get into theaters, she doesn't expect tighter scrutiny to have much effect.

Teenagers younger than 17 are ready for such films, according to Rocap. "What you watch on the news is worse than the movies," she said. "Once you're old enough to drive a car, you can choose what kind of movies you want to watch."

R-rated films also have been a standard part of Mike Becker's teenage years. In fact, he saw his first at 10. "They always seemed to be the good movies," said Becker, now 17. "If someone said, `Let's see a PG-13 film,' you'd laugh since it wasn't going to be any good."

Getting in was rarely a problem. "Even when I didn't look 17 and you could tell I was 13 or 14, I could go and buy a . . . ticket."

Becker would set the age cutoff at 15 or 16; it's unrealistic, he says, to think that high school students these days will see anything in movies they don't know about. Drugs, sex -- for many, it's already reality.

So, he asked, "why can't I watch it in a movie?"