FROM THE MOMENT he stepped in and brought new order and direction to Washington's public school system, Superintendent Vincent E. Reed has been pressing hard for tangible improvements in the academic curriculum, changes aimed at enlarging classroom opportunities throughout the city. One of his earliest and most important proposals was to create a rigorously academic four-year high school that would offer a wide range of grade levels as well as advanced studies in English, math, sciences, languages and history. For a number of reasons, however, the superintendent's experiment failed to get under way. Last week, the proposal again came before the school board for study, comment -- and maybe this time -- a decision to give it a try. We surely hope so.

Because some misunderstandings in the past have led to criticisms of his plan. Dr. Reed has been careful to note that the school he is proposing would be meant not just for the gifted student, but in large part for the average student who is working at grade level but who may not be sufficiently challenged by the classwork. The idea is to come up with a model educational program that could expand academic opportunities for students of all income levels.

Some people have voiced concern that such a facility might drain the best teachers and students from the rest of the high schools, or that certain programs in the other schools might be dropped once a new school starts offering the same or better. Dr. Reed believes that, on the contrary, there could be a healthy opposite effect -- successful classroom programs could be adopted citywide, and these in turn would attract good teachers to the entire school system.

The cold fact now is that too many good students have been leaving the system altogether for their secondary education. The retention of these students -- and the continued involvement of their parents in working for a better public school system -- surely would improve the reputation and record of achievements of the school system.

On the practical side, Dr. Reed says the model school could be established in any one of many buildings owned by the system. With a teaching staff of perhaps 70 out of some 7,000 teachers, the school would not have any monopoly on "good" teachers (however you define that term).

It's well worth a try. The city's other specialty high schools -- for the arts, for math and science, for marine science and for vocational skills -- have been well received. A successful academic program need not be unique or exclusive. If iy works as it should, it can be contagious and enormously beneficial to children of all classes. The District of Columbia public schools desperately need this larger sense of possibility -- and the new school board can begin right away to make it happen.