FOR THE third straight year, test scores are up in the District's public schools. The scores show strong improvement in the middle grades and steady improvement in the overall performance. For a school system that has had so many troubles over the years, and continues to have troubles in its leadership, the test scores are a welcome sign of accomplishment.

Typically the first-, second- and third-grade students have been within points of grade-level performance on standardized tests. The real problem has come with the older students. They have been far off the normal standard achievement. The greatest improvement on these latest test scores was among ninth graders who moved up one whole year from 7.0 in math to 8.0. While optimism about the improvement of elementary students must be tempered because it was only slight, the junior high school students should be congratulated. Typically, junior high school is where students begin to show how badly they have been prepared in the basics by flunking more advanced subjects and beginning the truancy, crime and other behavior that draws students away from school.

The good test scores in elementary school indicate that students now entering the schools are getting the basics of good education, and this holds hope for the future. Many of the problems of the public schools start in the lower grades when students never quite get a grip on how to add or how to read. Those inadequacies grow larger and meaner as the children are promoted. To give young children a solid hold on academics is the main job the schools have. Any evidence that the schools are doing better at accomplishing this job is good news for the entire city.