SLIPPING GRADES: Tasha Henderson, right, and her daughter, Coretha, pose outside their home in

SLIPPING GRADES: Tasha Henderson, right, and her daughter, Coretha, pose outside their home in Edmond, Okla., with the sign Coretha was forced to hold for an hour at a busy intersection so that passing motorists could read it. The 14-year-old freshman already has been forced by her parents to give up basketball and track because of slipping grades, and she said she hopes to improve in school so she can play next year. A5