Alexandria public school students scored slightly above the national norm on academic achievement tests, with schools attended mostly by higher income students outscoring schools serving mostly lower income students, according to a report last night to the City School Board.

However, the report indicated that in some cases schools with low achievement scores out-performed schools with higher scores when they were measured in relative gains students made in specific learning skills.

"When parents try to assess the educational quality of schools, they should not only look at achievement levels. That would be unfair," said James P. Akin, author of the report and executive assistant for the school system's research, planning and evaluation. "What parents should look at is growth, progress."

Based on the results of standardized tests given to almost 4,000 elementary and junior high school students last March, Akin said the report shows for the first time school-by-school breakdowns of those results.

The annual tests, from the Science Research Associates series, is required by state law.

Akin said his analysis of the results was done to help school administrators target trouble areas and chart progress.

Overall, the sampling of Alexandria students scored above the national average percentile of 50. Alexandria's fourth graders, for example, scored 57, a three-point improvement over last year; eighth graders scored 52, two points above last year, and 11th graders were two points below the national average, but two points better than last year's tests scores.

The school with the most outstanding tests scores was George Mason Elementary, where fourth graders averaged in the 87th percentile, meaning that their performance matched or exceeded 87 percent of students nationwide. George Mason, Adkin said, serves a mostly middle- to high-income community.

George Mason's reading, math and language skills scores were all in the low to mid 80 percentiles, according to the report.

Akin called the test results from John Adams Elementary School equally or perhaps more impressive, although 37 points lower than George Mason's.

John Adams, which serves a much more economically diverse student body and receives lower income students bused across town from the Cora Kelly Elementary School area in central Alexandria, showed a 55 percent gain using a nationally recognized growth formula, while Mason showed a 46.5 percent gain.

"There should be a focus on gains students made," Akin said. "The schools with the highest scores are not neccessarily the ones with the highest gains."

Akin said achievement test more often measure a students' socio-economic background rather than real classroom performance. He said students from higher income backgrounds tend to have more exposure to learning than their lower income counterparts, a difference that leads to a gap in achievement levels in school.

Last year, Alexandria Superintendent Robert W. Peebles issued a directive to his staff to improve areas in which prior years of testing indicated weaknesses.

In other action, the board scheduled a public hearing for 7:30 p.m. Oct. 12 to hear comment on possible changes in the school system's 10-year-old busing plan.