Never Been Kissed (1999)

Josie Geller, a baby-faced junior copywriter at the Chicago Sun-Times, must pose as a student at her former high school to research contemporary teenage culture. With the help of her brother, Rob, Josie infiltrates the inner circle of the most popular clique on campus. But she hits a major snag in her investigation -- not to mention her own failed love life -- when she falls for her dreamy English teacher, Sam Coulson.