AFTER MANY YEARS and more than a few misunderstandings, the city's school board has given preliminary approval to an important proposal championed by Superintendent Vincent E. Reed -- to create a rigorously academic four-year high school. The idea is to offer a wide range of grade-level work, as well as advanced studies in English, math, sciences, languages and history. Before various groups leap to kill it, Dr. Reed should be given a fair chance to give his plan a try.

The most common misunderstandidng is that Dr. Reed is seeking to divert money and resources to some elitist plan to separate students by some warped and snobbish standards of intelligence, class, race or geography. Not so. What the superintendent has recognized is that all children in the District -- and especially those who have no alternatives to the public schools -- deserve the opportunity of an education system with a larger sense of academic possiblity. Precisely because a successful program doesn't have to be unique or exclusive, whatever turns out to work well in such an experiment can spread to every high school in the city. As for the new school, it could be open to any students -- without entrance exams, but on the condition that those who could not perform the work could be dropped.

There has been understandable concern that a new school might drain the "best" teachers and students from the rest of the high schools, or that certain course offerings might be dropped once a new school starts offering the same or better. On the contrary, Dr. Reed has stressed that a new school would have no monopoly on talent. The difference would have to do with curriculum and course emphasis.

There already exist other impressive examples of specialty high schools in the District system -- for the arts, for math and science, for marine science and for vocational skills. They have challenged young people of varied talents from all over the city and sent many of them on to college and successful careers. Still, too many students have been leaving the system altogether for their secondary education; still others would if they could. Their continued involvement -- along with their parents' -- in supporting the public schools could improve the reputation and record of achievement of the system in so many significant ways.

That is why it is so important for people who want the best public education possible for this city's children to understand and support Vincent Reed's effort to do something about it.