UP THE DOWN STAIRCASE by Bel Kaufman (HarperPerennial: $8.95). Bel Kaufman's best-selling account of a teacher's first year at an inner-city New York high school began as a three-page story in the Saturday Review of Literature in 1962; when the novel appeared in 1964, it seemed so sharply observed that many readers assumed the book was a thinly veiled autobiography. Twenty-seven years later, Sylvia Barrett's daily encounters with self-important administrators, reams of inane paperwork, substandard equipment and unprepared students remain entertaining. However, the difficulties she encounters, including "an epidemic of chalk-stealing," seem very mild compared to the present, lugubrious state of the American educational system. The problems that the author describes have been exacerbated through 25 years of under-funding, neglect and bureaucratic chicanery. In her introduction to the new edition, Kaufman observes, "Schools today are exactly the same as they were over a quarter of a century ago, only now they are more so. Everything described in my fiction is today reality. Only computers and condoms are new."