A baby-faced eighth grader, viciously bullied online, hangs himself. With a click of her mouse, a young woman with anorexia uses cyberspace to find tips on starving. A high school student, with a world of plot outlines available on the Internet, admits that he cannot recall ever actually reading a book.

If 21st-century parenthood is not scary enough, “Growing Up Online,” a documentary to be broadcast on the “Frontline” program on most PBS stations on Tuesday night, uses those real-life stories to ask an increasingly important question: What does it mean to be part of the first generation coming of age steeped in a virtual world seemingly outside parental control? The documentary touches on the much discussed fear of online sexual predators, as well as concerns about the ease of cut-and-paste plagiarism, using the Internet. It also examines how notions of privacy and the meaning of friendships change when a computer button can ferry your words and your images to strangers.

“It’s one of those societal shifts that’s happening so quickly there’s not a lot of good data on what this means for our kids’ brains or hearts,” said Rachel Dretzin, the writer of “Online.” Her documentary credits include “Failure to Protect,” a series about Maine’s child welfare system, and “Hillary’s Class,” about the 1969 Wellesley College graduating class that included the future Senator Hillary Rodham Clinton. (Ms. Dretzin has also produced a 15-minute video on middle-aged sexuality for nytimes.com.)

Ms. Dretzin co-produced and directed “Online” with John Maggio, whose documentary work includes “Ten Days That Unexpectedly Changed America: Einstein’s Letter,” part of a series on the History Channel.