7th Heaven (1996) : 5x4

Exasperation reaches an all-time high in the Camden household, as Eric and Annie helplessly watch their oldest daughter Mary and her worrisome friends continue to head down the path of destruction and into the hands of the law. When Frankie (guest-star Chyler Leigh) expresses interest in signing up for college classes Mary starts checking out Lucy's early application packets. Meanwhile, Simon has a hot date and Lucy gets a weird proposition from a classmate. Lastly, Ruthie discovers manipulative fun of keeping a diary--- much to the embarrassment of Eric and Annie when she sees them having SEX!