For the first time in six years, the Washington school system has released school-by-school scores on standardized tests for the city's 160 elementary and junior high schools.

The multiple-choice tests in reading and mathematics were given last May to about 34,000 students in the third, sixth and ninth grades.

Compared to tests given a year earlier to a 10 percent sample of students, the system-wide averages were virtually unchanged at levels far below the national norms. By ninth grade, the D.C. averages were three years below the norms in both reading and math.

Averages for individual schools, however, varied widely. At a few elementary school west of Rock Creek Park, students averaged in the top 20 percent nationwide and were several years above the national norms. At many other schools throughout the city, averages were substantially belwo the norms, and some were in the bottom 20 percent nationwide.

Generally, the results followed the income and educational level of the neighborhoods where children lived. But many schools that were near each other - and whose pupils were similar - had significantly different results.

For example, at the Reed Elementary School (formerly Morgan), 18th Street and Wyoming Avenue NW, sixth graders were two years below the national norm in mathematics and 2.5 years below in reading.

At Adams Elementary, just two blocks away at 19th and California streets NW, students still had academic problems, but they were substantially less severe. The average scores for Adams sixth graders were one year below the norm in math and 1.8 years below in reading.

At Noyes Elementary, 10th and Franklin streets NE, sixth graders were four months above the national norms in both reading and math. Scores at Brookland Elementary, Michigan Avenue and Randolph Street NE, were more than a year below the norm even though Brookland had a much smaller proportion of low income children.

In the Chevy Chase area, third grade scores at Murch Elementary, 36th and Ellicott streets NW, were about, a half-year above those at Lafayette, Northampton Street and Broad Branch Road NW, although children at both schools did well. Sixth graders at the two schools had an identically high average in reading - 10.4 - but in math the average was 10.9 at Murch and 8.8 at Lafayette.

All the scores are expressed in grade equivalents based on nationwide norms for each grade tested. Since the tests were given early May, during the eighth month of the school year, the norms were 3.8 for third grade, 6.8 for sixth grade, and 9.8 for ninth grade. Each 10th of a grade in a test score is equivalent to the achievement expected in one month. Thus, a sixth grader who scored 6.0 would be 8 months below the national norm.

In a press release accompanying the new scores, Superintendent Vincent Reed warned against using the results "as the sole measure for evaluating schools because of the many variable factors that tend to influence them, such as class size, socioeconomic level and student and teacher attendance." But Reed said the scores would be a useful "benchmark" to measure progress.

The tests used were the Comprehensive Test of Basic Skills, published by the California Testing Bureau, a division of McGraw Hill. Each contained 183 multiple-choice questions. Children were give about two hours to answer them.

All school districts in the suburbs give similar tests and make public the results for individual schools. In Washington, no scores were available for high schools because standardized tests were not given in them last year.

In the charts below, the figures given for each school are medians. Median means that half the students were above the score listed and half were below it.