Arlington and Alexandria reported gains in average math scores on the 2005 SAT, while average verbal scores dipped slightly, according to results released last week.

In Arlington, the average score on the verbal portion of the test decreased by two points, from 543 to 541, and the math average increased by two points, from 542 to 544, for an average combined score of 1085.

In Alexandria, the average verbal score was 482 and the average math score was 481, for an average combined score of 963, the lowest overall score among major Northern Virginia school systems.

Nationwide, the average verbal score was 508, unchanged from last year. The average math score rose from 518 to 520. Math scores reached a record high this year nationwide, as well as in Virginia, where the average math score increased five points.

This is the last year that student performance will be measured using the two-part version of the test, which has a maximum score of 1600. Beginning next year, the College Board will report the results of seniors who took a new version of the test, which has a maximum of 2400 and requires students to write an essay.

In Arlington, scores have been increasing over the past decade, and the county's scores exceeded the national and state averages. Schools Superintendent Robert Smith said he was pleased to see the overall averages remain steady, even as participation in the test had increased by about four percentage points, to 73 percent.

However, Smith said he was troubled by figures showing a decrease in participation and average scores of black students.

According to school system data, participation by students identifying themselves as white increased by 37 percent, while participation by Hispanic students increased by 44 percent. At the same time, black student participation declined by 13 percent and Asian student participation declined by 4 percent.

"We will carefully examine these results to determine what our next best steps need to be," Smith said.

In Alexandria, overall scores have declined over the last decade. This year's average math score increased seven points, while the average verbal score decreased one point.

"It's good to see that trend in math going in an upward direction," said T.C. Williams Principal John Porter. Alexandria school officials are still awaiting data that breaks down T.C. Williams's results by categories such as ethnicity and sex.

Noting that T.C. Williams's scores were lower than the state and national averages, Porter said the school's demographics were a factor. "We test a larger percentage of students for whom English is not their first language, and we test a larger number of families who are deemed to be at a socioeconomic disadvantage," he said.