MGM and producer Jennifer Klein made a preemptive purchase of “F+,” a spec script for an urban classroom comedy about the unlikely friendship between the nastiest teacher in high school and a student who makes his life a living hell.

Klein will produce through 3B Prods.

The script was written by Joe Ballarini, who is being eyed to direct the pic. Ballarini most recently scripted a remake of “The Blob” for Warner Bros. and producer Jon Peters and rewrote “Spooks” for Miramax. He also wrote “The Legendary McClouds” for Paramount and “The Spy Next Door” at Dimension.

Since forming her 3B shingle with a first-look deal at MGM, Klein has set up the pics “Don’t Tell My Mother” and “Scrawl” at the studio and is developing “Truce” at Warner Independent Pictures.