Public school students in the District of Columbia had the lowest college board test scores of any Washington-area school system last year and scored more than 200 points below national averages.

In fact, D.C. students placed in the bottom 20 percent among all students taking the tests nationwide, according to reports released by the D.C. school board.

Seniors in the school system last year averaged 326 on the verbal portion and 353 on the mathematics section of the Scholastic Aptitude test, the reports said.

The nationwide averages for the same tests were 427 in verbal and 467 in mathematics.

Scores range from 200 to 800 on each part of the three-hour, multiple choice examinations.

The new scores for the District of Columbia are the first to be released since 1975, when then-superintendent Barbara Sizemore, who opposed standardized testing, stopped asking for the results from the college board.

Superintendent Vincent Reed said last month he was again asking for the scores because "we ought to know how our students are doing."

The D.C. test scores were the lowest of any Washington-area school system. Reports released by the suburban school systems last month show that college entrance scores fell last year throughout the Washington area.

But the scores remained substantially above the national averages in all suburban school systems except Prince George's County.

The new reports show that during the three years when the D.C. scores were unreported, they remained almost the same, rising and falling within a range of 7 points.

The total score in verbal and math combined for the D.C. seniors of 1979 was just four points below that of 1975. Nationally, there was a steady decline of 12 points over the same period.

The average 1979 college board scores for the Washington area were as follows: (TABLE) (COLUMN)Verbal(COLUMN)Math(COLUMN)Total Arlington(COLUMN)465(COLUMN)498(COLUMN)963 Fairfax(COLUMN)460(COLUMN)502(COLUMN)962 Montgomery(COLUMN)456(COLUMN)500(COLUMN)956 Falls Church(COLUMN)453(COLUMN)492(COLUMN)945 Alexandria(COLUMN)439(COLUMN)482(COLUMN)921 United States(COLUMN)427(COLUMN)467(COLUMN)894 Prince George's(COLUMN)406(COLUMN)450(COLUMN)856 District of Columbia(COLUMN)326(COLUMN)353(COLUMN)679(END TABLE)

"We're trying to analyze what these thest scores mean," said deputy D.C. school superintendent Elizabeth Yancey. "We seem to be on a plateau right now, but we hope [students] will become so conscious of the scores that they will improve . . . I would like to predict there will be gains next year because people are conscious of them."

The College Board report on D.C. public schools includes scores from 16 public high schools. It omits the city's newest senior high, Woodson, which opened in 1974, and five new special programs that award high school diplomas, including the "School Without Walls."

College Board officials said they did not know why these scores from an estimated 300 students were left out of the report. They said they did not know what effect they might have on the overall average for the school system. Yancey said she thought the missing schools might raise the system-wide averages slightly.

In a separate report, the College Board said the average score for all students attending school in Washington -- both public and private combined -- was 381 on the verbal part of the SAT and 401 in math.

Only 35 D.C. public school students scored above 600 points on the verbal part of the test and only 36 did that well in math. On the other hand, 1,168 scored below 300 points in verbal and 820 below 300 points in math.

About 90 percent of the D.C. public school students taking the test were black, the College Board reported. Half came from families with an income of less than $11,400 a year, compared to an average income of $20,800 for all students taking the test nationwide.

"We're not saying the tests are biased by income factors," said deputy superintendent Yancey. "There is a body of knowledge that all students need to know. But it is readily apparent that if you are from an affluent middle-class background, there are certain things you are going to learn from your family outside the classroom. That's a given.

"The problem for the schools is to expose all other youngsters to the same wide body of knowledge," she said. "That's what we are trying to do."