"Teachers" is an erratic comedy set in today's blackboard jungle, with the ever more dissipated Nick Nolte as an understanding instructor. It's a little like "Fast Times With Mr. Chips." Part screwball, part sensitivity training, it works when it's not preaching about the system.

Nolte, his jowls daubed with blusher, his hair long and greasy, doesn't really look like a social studies teacher. He looks like a boxer gone to fat. And he's often so hoarse you can barely hear him. Still, Nolte's so good that he squeaks by, which he's been doing ever since "48 Hrs."

Costar Jobeth Williams gets by, too. She plays a former student grown into an idealistic lawyer who's suing her alma mater, John F. Kennedy High School, on behalf of an illiterate graduate. Williams, embarrassed by a needless nude scene, is no match for Nolte. Shared scenes, eant to convey sexual tension and the conflict of ideas, are flat and stale.

Her gullibility contrasts with the hard-nosed realism of the vice principal, forcefully played by Judd Hirsch. His excellent performance and those of the strong supporting cast carry the film. Richard Mulligan is especially fine as a missing mental patient who becomes a substitute teacher, as is Royal Dano, who dies on the job but nobody notices till third period.

They've got more star power than they need, with Ralph Macchio, doubtful as a delinquent when everybody knows he's really "The Karate Kid." Nolte, his mentor in this film, is drawn back into the fight for quality education when Macchio, as his social studies project, exposes corruption in the corridors.

The differing points of view, set up by young scriptwriter W.R. McKinney, are well-drawn, but equivocal. McKinney's for good schools, but nobody's really liable for bad ones. That may work in a term paper, but not at the movies.

The customary rock soundtrack recording will release simultaneously with the film. Like "Teachers," it gets a C average. TEACHERS -- At area theaters.