The average SAT score for Prince William County seniors dropped slightly this year compared with last, and trails the state and national average.

Prince William's average score on the verbal part of the test was 514, and the average math score was 502, for a total of 1016 out of 1600. The average last year was 515 verbal and 504 math for a total of 1019. The Virginia average this year was 515 verbal and 509 math for a total of 1024, and the national average was 508 verbal and 518 math for a total of 1026.

Manassas Park found itself in a similar situation to the county's: The seniors at Manassas Park High School had averages of 484 math and 454 verbal, for a total of 938.

Only Manassas's Osbourn High School beat or matched both the state and national averages, with scores of 518 math and 522 verbal for a total of 1040.

The SAT, administered by the New York-based College Board, is taken by high school students applying to college. In the spring, the College Board will add a writing test to the math and verbal sections.

Prince William administrators, whether in schools that showed improvement or not, were hard-pressed to explain the difference between this year's performance and last year's. They said that the SAT shows only a snapshot of student performance, and results are most valuable when examined over time.

Brentsville District High School showed the greatest improvement, moving up to a 1081 combined score this year compared with 1058 the year before.

Principal Michael Mulgrew said that he doesn't look at the test on a year-to-year basis, however. He prefers to examine scores over several years.

"The pendulum should be on the upswing," Mulgrew said. "Over a four- or five-year period, have we increased the academic rigor in this building? Yes."

Stonewall Jackson High School showed the largest drop, with a combined score of 1010 this year compared with 1039 the year before. Principal David Huckestein said that he examines SAT scores in combination with a variety of other tests the students take, in order to gauge the school's progress. Although SAT scores are down, Advanced Placement test scores have been improving, as well as scores on International Baccalaureate tests. Eighty-four percent of the IB tests taken at the school earned scores of 4 or higher on a 7-point scale, making students eligible for college credit similar to AP tests.

"Our students here are successful, and we've proven that," he said.

Bruce McDade, principal of Manassas Park High School, said the entire school district is working to introduce SAT rigor even earlier than high school.

"You can't start in ninth grade," McDade said. Some of the plans include introducing SAT vocabulary words to students in middle school and pushing more students to take advanced math courses. In addition, for the past two years the city has paid for students to take the preliminary SAT as a sophomore.

Sandy Thompson, director of instructional services for Manassas schools, said the district is pleased with the progress at Osbourn. "We're comparable with many schools around us, and higher than many," she said.

She has also seen many Osbourn students go on to schools with national prestige. "We have seniors going to Duke and Princeton. That's probably one of the more positive things we've seen," she said.