(CNN) -- Math and reading scores for fourth- and eighth-graders in public schools improved nationwide, but African-American students continued to lag behind their white classmates, a new federal study found.
Based on a 500-point scale, African-American students scored on average 26 points less than white students on their reading and math tests, according to the U.S. Department of Education's National Center for Education Statistics. The center based its findings on the National Assessment of Educational Progress, a federal measure of student achievement in math, science and reading.
While the achievement gap narrowed in some states as African-American students academically improved more than their white counterparts, the gap still remained, the study found.
The report's analysts used school registration forms that state a child's race, said Arnold Goldstein, the director for design analysis and reporting at the National Center for Education Statistics. Students whose race was anything other than African-American or white were not included in the study, he said.
The national reading average for African-American fourth-graders was 203 points, compared to 230 points for white students. West Virginia had the smallest achievement gap, at 13 points, and Washington, D.C. the largest, at 67 points.
For eighth-graders, the national average was 244 points for African-American students and 270 points for white students. West Virginia and Nevada tied for the narrowest gap at 15 points, while Wisconsin had the widest gap with 38 points.
The national math average for African-American fourth-graders was 222 points, compared to 248 points for white students. The smallest achievement gap was in Hawaii and West Virginia, at 14 points. The highest gap was in Washington, D.C., at 54 points.
For eighth-graders, the national average was 259 points for African-Americans and 290 points for white students. Oregon had the narrowest gap at 16 points, while Nebraska had the widest gap, at 51 points.
While the racial divide headlines the report, some attribute the achievement gap to several factors, including socioeconomic differences and the standards of quality education.
"[U.S. Secretary of Education Arne Duncan's] observation is clearly that schools in high poverty, minority neighborhoods typically have the biggest challenge to recruit and keep experienced teachers," said John White, Department of Education spokesman.
"Schools in low-income neighborhoods have trouble attracting and retaining teachers, and that's where it becomes difficult to give kids what they need to be high-performing, when they have in some cases less experienced teachers," he added.
As some teachers rack up more experience, they may move to better-performing schools in higher-income areas, said White, thus diverting needed experience away from areas that need it most.
As an incentive, a federal grant supports financial bonuses to teachers whose students perform better, White said. The strategy emphasizes the importance of having well-qualified educators in the classrooms.
"Kids are the same everywhere. It doesn't matter where they live, it doesn't matter what color they are. What matters is the level of teaching in the schools," he said.
The focus on quality teaching and education strategies is an effort to control what happens inside the school building, because administrators cannot control what happens outside of it, said Tyra Newell, executive director of the Greater New Orleans Program of New Leaders for New Schools, an organization that works with principals in urban communities.
Newell said since children in low-income, minority neighborhoods already face challenges associated with poverty, such as fewer enrichment opportunities, it is even more important to support academic methods that work.
"Society can pay for it now, or they can pay for it later," Newell said. "And they can pay for it by looking at our prison system, by looking at a shortage of talent in our workforce. And so when they look at it, not preparing all of our children now will affect us all later."
Although the federal government has marked significant achievement gaps between African-American and white fourth- and eighth-graders since 1978, according to the report, Kevin Huffman of Teach For America insists that the problem is solvable.
Students, no matter their background, can perform well when given "the opportunities they deserve," said Huffman, the organization's executive vice president of public affairs.
His organization, which describes itself on its Web site as a corps of teachers who commit to teach in urban and rural public schools for two years, is an example of that.
High school students taught by Teach for America teachers performed better than other students on statewide tests in math and science, according to a 2008 study by the Urban Institute, a research organization. Teach for America's educators, who are more often new teachers, work in mostly urban and rural-area schools.
Aside from the short-term scores-oriented effect of narrowing the achievement gap, the long-term effect is one of a moral and economic obligation, Huffman said.
"One of the greatest assets that the United States has is its diversity," he said. "And if we can live up to being a land of equal opportunity, the advantage that we'll have over other countries that don't even aspire to that level of equity is going to be profound."
CNN's Lateef Mungin contributed to this report.