The District's school system last week released the results of its most recent Comprehensive Test of Basic Skills, which was taken this spring by 3rd, 6th, 8th, 9th and 11th graders. Overall, the scores showed significant improvement over those of last year in the five sections on reading, mathematics, language, science and social studies.

Third and sixth graders scored the best in comparison with their national counterparts. Third graders exceeded national norms in all five test areas, while sixth graders failed to surpass the national norm only in social studies.

Ninth and 11th graders, while still falling below the national norms, showed the greatest improvement, raising their grade-level equivalent scores above those of last year's students in the District by as much as a year and two months.

Reading, math and language tests were given to eighth graders for the first time this year, so there is no basis for comparison.

D.C. School Superintendent Floretta D. McKenzie attributed the higher scores to increased dedication from teachers, a current year schools budget that allowed for additional classroom teacher aides and community support in the form of nearly 9,000 volunteers who mainly worked tutoring youngsters. Increased emphasis on test-taking skills also was a factor, McKenzie said.