TO NO ONE'S surprise, Fairfax County -- well known for high-performing high schools -- announced earlier this month that its schools had done exceptionally well on this year's Virginia Standards of Learning exams. The tests, in English, math, science and history, established that 95 percent of the county's schools meet the state standards for full accreditation, up from 89 percent in 2002. This improvement was achieved despite tougher accreditation requirements this year.

It's a record to be proud of. It is not, however, proof that all of Fairfax's students are doing well. Looking beyond the impressive overall scores and focusing on the scores when they are broken down by "subgroup" -- something the county is required to do by the much-reviled (in Virginia) No Child Left Behind Act -- a different picture emerges. Using information that the county is required by the law to publish on the Internet, one Fairfax parent, Maria Casby Allen, discovered that minority-group achievement throughout the county remains lower than white achievement. More striking was her additional discovery that minority test scores, particu- larly African-American test scores, remain significantly lower in Fairfax than in other Virginia school systems, including some, such as Richmond's, which are predominantly black and not as respected as the Fairfax schools.

Why should this be? A spokesman for the Fairfax school system, which is about 10 percent African American, said that administrators know about the disparity Ms. Allen discovered and can't explain it. But "if we can learn something from Richmond, we will," he said. Some observers think the better scores in Richmond come from the use of teaching methods -- frequent testing and feedback -- that are known to work best for low-income and minority students.

Whatever the explanation, greater thought needs to be given to how best to educate the county's low-income students. Certainly some of the current solutions, such as rules that allow students to transfer out of schools classified under No Child Left Behind rule as "failing to improve," are insufficient. According to a recent Post story, it is now more common for successful students in Fairfax and across the region to apply for such transfers, and for weaker students to stay behind. Were the county's school administrators to concentrate harder on the "failing" schools, and the failing students within them, and to ask deeper questions about the significance of their own statistics, more lasting solutions might be found.