And now Baltimore has joined the list of cities where public-school test scores, after an alarming drop, are on the upswing.

Four years ago, Baltimore students in grades two through eleven averaged 20.2 months behind national norms in reading, 17.4 months in math. (That is a substantial average deficit, considering that in the early grades there are limits to how far behind a child can fall; a second-grader can't be more than a year behind.)

When the standardized tests were administered this past spring, the reading lag was 5.7 months. In math it was .3 months--in effect, right at the national norm. What makes that news particularly exciting is the fact that, until just a few years ago, test scores had been on a fairly consistent decline.

What has happened? Superintendent John L. Crew, no doubt anticipating the question and perhaps not averse to a bit of horn-tooting, recounts the effort in a recently published booklet: "Effective Public Education: The Baltimore Story." The details may be of interest mainly to educators, but the heart of the program is simple enough: tough standards and tender concern.

"We had our people write learning expectancies in reading, writing and math for each grade, so that each teacher would know exactly what was expected," Crew said in a recent interview. "We made it a matter of policy that every child would have homework. Then we began placing our children according to their test results. Students who scored less than 40 percent on the reading proficiency test, for instance, were assigned a reading clinician in addition to their regular language arts program."

Two things illustrate the mix of toughness and tenderness that Crew says is responsible for the system's impressive gains. He introduced a new reading- through-drama program in which poor readers read and act out plays on subjects of particular interest to their age group. And he relieved three principals of their duties in mid year.

But more important than any of the particulars is the changed attitude that has hit Baltimore and appears to be sweeping the country. Crew puts it this way:

"In the 1960s, everything was develop- at-your-own rate, whole-child, progressive education. We were wrapped up in educational innovation and decentralization and other political issues, with really no defined goals and objectives. As educators, we are learning that you must have structure and objectives, or your program simply won't work.

"There's one other thing that I think is important: we've got a bunch of black superintendents who have the personality to handle the politics, which leaves them free to run their systems. I think you'll find that that is a substantial part of the academic progress that is being made here and in Newark, Detroit, Atlanta, Memphis, St. Louis, Minneapolis, Washington and Richmond."

Black superintendents, he said, partly because they know the political ropes and partly because they are black, can hold black kids responsible in ways that few white superintendents could, for fear of being accused of racism.

There may be one other important piece of good news. As more big-city superintendents, principals and teachers discover that inner-city children can learn if they are held to standards and given the necessary help, the pressure for academic improvement will spread. The encouraging evidence is that results will follow.

After a decade or more of pitying "disadvantaged" children and excusing their failure, we are learning again that ancient, obvious lesson: the compassionate act is not to excuse but to teach.