The achievement gap between white and black students on the SAT is five times as large at Annapolis High School as at Southern High School in Harwood, illustrating that the goal of racial parity may be more easily attained in some parts of the county than others.

The SAT achievement gap is essentially unchanged in Anne Arundel County over the past three years, based on a review of scores from 2003 to 2005 for white and black students. The gap has narrowed at four schools in that time span, but it has widened at six others, among the 10 high schools with sufficient numbers of black students to warrant a comparison.

In the county as a whole, the gap between white and black students on the college admissions test hovers just under 100 points, based on 2005 data, meaning that the average white student scores nearly 100 points higher in both the verbal and math sections of the exam, out of a possible 800 points on each.

The 2005 SAT report, released last week, showed a widening gap between performance of black and white students nationwide over the past decade. In math, for example, the average score among black students has risen nine points in the past 10 years, but the average score among white students has risen 15 points.

While the performance gap in Anne Arundel County hasn't changed much in the past three years, the county has improved on another measure that is considered equally important among testing experts: participation. The number of black students tested in Anne Arundel has increased by two-thirds since 2003, from 213 that year to 356 in 2005.

"The participation has gone up; the performance has remained the same," said Adam Milam, who oversees testing in Anne Arundel schools. "But when we look at how many more kids" are taking the SAT, "that's a very positive thing."

Increasing participation has been a primary focus of Anne Arundel Superintendent Eric J. Smith, who announced Tuesday that he will be leaving his post to take a job at Harvard. Under his leadership, the school system has generally increased minority participation in both the SAT and, especially, the Advanced Placement program, which challenges high school students with college-level work.

Black students in the Class of 2005 scored an average 890 on the combined verbal and math sections of the SAT, 195 points lower than the average score attained by whites, 1085.

But the gap was much larger at some high schools, and much smaller at others.

Southern High School, with the smallest achievement gap, had an average score of 1002 for black students and 1061 for whites, a difference of about 30 points on each section of the test. Southern High has closed the gap since 2003, when black students scored about 60 points lower in both verbal and math. The school is about 15 percent black, and participation in SAT is on the increase.

"I think we're just doing a much better job at communicating with both students and parents about the importance of the SAT test," said Jason Dykstra, principal of Southern High. "We have more African Americans taking the test, and that's part of our goal."

Meade High School, with a much larger black population, has reduced its achievement gap from 87 points to 61 during the past three years of SAT scores. Black students averaged 461 in verbal, 462 in math in 2005; whites, 524 verbal, 521 math. SAT participation at Meade is 53 percent, a bit higher than at Southern High. Higher SAT participation tends to yield a somewhat lower average score.

"Meade represents, to me, the shining star of the group," Milam said, because of its success in narrowing the achievement gap while also increasing participation on the test among black students.

Three Anne Arundel high schools -- Annapolis, Old Mill and Severna Park -- have achievement gaps of more than 100 points on the SAT, based on white and black performance in 2005.

Black students at Annapolis High averaged 832 on the SAT in 2005, almost 300 points lower than the average for whites of 1123. The gap has increased since 2003, when the scores of blacks and whites at the school were about 100 points apart on each section of the test.

But SAT participation is strong at Annapolis High, where 62 percent of seniors in 2005 took the test, well above the countywide average of 54 percent. That reflects the superintendent's philosophy, Milam said, that "participating in these tests is a major, major step for these kids."