FOR THOSE WHO may have missed the week's least fascinating finding from academe's lo-and- behold school of research, it has been discovered that the District of Columbia's school system has a larger percentage of black students than any other big-city system in the country. In confirming the obvious, a report by a University of Chicago professor for the Joint Center for Policy Studies goes on to label this "the most segregated" system--which, as columnist William Raspberry has suggested, is true if you consider only the blackness, not the whiteness, of a system as the measure of segregation and of the need to lighten up a student body's racial composition.

We don't look at it that way. Nor do we buy any assumption that to improve, the District schools must find a way to pull in more white students from the suburbs. For that matter, more than a few school administrators, teachers, parents and students have noted that good things seem to be happening already in this 94-percent-black school system now that there is a strong superintendent working with a thoughtful board of education.

Rather than seek congressional financing to allow D.C. students to attend suburban schools without paying tuition, as the report urges, the school board should keep to its primary mission, accurately described by board vice president Nathaniel Bush as being "to provide the best education we can for the students we have."

There's nothing wrong with cooperative exchange programs involving the various metropolitan school systems. In fact, there have been some, as well as other joint ventures described by Alexandria Superintendent Robert W. Peebles and former D.C. superintendent Vincent E. Reed on our editorial pages this week. If one jurisdiction can make available to others a specialized educational program or a curriculum not offered elsewhere, so much the better. But no children, black or white, should be led to believe that blackness is a sign of weakness in a student body.