AFTER ALL THE HIGH MARKS that Vincent E. Reed's administration has been winning for shaping up Washington's public school system, it's somewhat disconcerting to read, as we did just the other day, that certain classroom programs are being subjected to an eleventh-hour shakeup. All of a sudden - in fact, on the very morning when teachers were reporting back to work last week - 70 tenured teachers, including two-thirds of all the foreign-language teachers in the elementary-school system, two of whom had 17 years' experience - were told they won't have jobs after the end of this month. Quite aside from what these layoffs are set to do to the city's language programs, both the timing and the way in which the decision was made were bad.

Officials say these layoffs have to to be made because of a decrease in enrollment and a cut in teaching positions. They say they delayed sending notices until Thursday because they hoped enough other teachers would retire to avoid any layoffs. It's the first time in at least a decade that tenured teachers are scheduled to be laid off.

One may argue, of course, that training in French, Spanish, Latin and other languages in elementary school os a frill. We would agree with the members of the school board that teaching in the basic skills is a priority. But a decision to decimate a program is one that should be voted upon directly by the elected school-board members - and should be not effected by the superintendent without review. As it stands, the elementary-school foreign-language program stands to lose 19 of its 32 teachers. Also, 18 of the city's 70 teachers in the elementary music programs are scheduled to be cut along with some art and physical-education teachers.

In making these cuts, the administration has managed to (1 dump 70 tenured teachers on the market a month into the academic year - a terrible time to find new jobs, and 2) effectively gut an academic program. Granted, there is no question that in the face of declining enrollments, cutbacks are going to be in order. But across-the-board killings of citywide programs - sometimes in schools where enrollments may not even have declined significantly - are not the sort of developments that attract parents to the system or please those whose children already are in it. The school board meets again on Sept. 21, and we urge the members to take a hard look at last week's staff decision and do everything possible to protect the experienced teachers who have been contributing in important ways to the all-round education of this city's children. We continue to believe that the District's public school system is on the upswing. But decisions such as last week's only serve to erode the valuable public confidence that officials have been working so hard to build.