Up the down staircase / by Bel Kaufman.

Enhanced descriptions from Syndetics:

Bel Kaufman's Up the Down Staircase is one of the best-loved novels of our time. It has been translated into sixteen languages, made into a prize-winning motion picture, and staged as a play at high schools all over the United States; its very title has become part of the American idiom.

Never before has a novel so compellingly laid bare the inner workings of a metropolitan high school. Up the Down Staircase is the funny and touching story of a committed, idealistic teacher whose dash with school bureaucracy is a timeless lesson for students, teachers, parents--anyone concerned about public education. Bel Kaufman lets her characters speak for themselves through memos, letters, directives from the principal, comments by students, notes between teachers, and papers from desk drawers and wastebaskets, evoking a vivid picture of teachers fighting the good fight against all that stands in the way of good teaching.