“Night School” (** out of four) was a mild comedy about an underachiever (Kevin Hart) who starts attending night school in hopes to obtain his G.E.D. and his teacher (Tiffany Haddish) is no-nonsense and has about as much sass and attitude as he does. Disappointing teaming of Hart and Haddish has only occasional chuckles and is utterly predictable. Haddish’ enthusiasm and charisma helps make this watchable but Hart can play this role in his sleep by now. Keith David has a funny cameo as Hart’s father.