AFTER MUDDLING through a crippling teacher's strike that lasted nearly a month this spring, Washington's ever-struggling public school system wound up the year with some surprisingly encouraging reading and mathematics test scores. Though most of the results still were well below national norms, they marked a dramatic turnaround of what had been a general downward drift for some years; and in all three grades tested -- third, sixth and ninth -scores in both reading and math were up. Though ninth graders still scored nearly three years behind in reading and math, the third-grade results are most heartening: These young students scored only two months below the national norm in math and six months below in reading.

But every bit of his progress, as well as any other improvements in classroom teaching, are in immediate jeopardy. With six weeks until the schools are scheduled to reopen, the school board and the teachers' union are nowhere near agreement on a new contract. A court-ordered fact-finding panel is due to issue recommendations by the end of this month, but its findings will not be binding. Barring some sudden outbreak of mature board-union understanding, the authority to prevent another tumultuous disruption of a school year is likely to rest with Superior Court Judge Glady's Kessler, who successfully ended the spring strike by ordering the fact-finding and an extension of the old contract.

Without continued judicial pressure, the situation could easily degenerate into another destructive board-teacher war. Neither the board's commendable objective of greater control over grading, discipline and other education policies nor the teachers' understandable refusal to work longer days and school years without some compensation can be advanced significantly until next year, when the board acquires some authority to negotiate salaries. In the meantine, the old contract should be kept in effect, even if it takes another court order.