Katie Couric talks to teens about their sexual attitudes. "There's a dramatically different paradigm," says Couric---it's more matter-of-fact and "we wanted to make sense" of it, so she spent a November weekend in Key Biscayne, Fla., with 20 youngsters (ages 13-17) from around the country. Think of the hour as a primer for parents. "It was designed to help parents understand what kids are thinking and doing," she says, "and how best to deal with it."