Kids in the U.S. are improving in reading and math, with low-achieving students making the biggest gains.
The 2008 scores come from the National Assessment of Educational Progress, a federal test considered the benchmark of how students perform across the country. In a report issued Tuesday, reading and math scores were measured against long-term trends.
Results were particularly noticeable on reading. Reading scores tend to lag behind math scores, but in 2008, students in every age group — 9, 13 and 17 — made gains. That hasn't happened since 1975.
In math, scores improved for younger children, but scores for 17-year-olds remained flat.
Education Secretary Arne Duncan said he was pleased but not satisfied with the results.
"We still have a lot more work to do," Duncan said. "Our focus on raising standards, increasing academic rigor and improving teacher quality are all steps in the right direction."
Results were in line with long-term trends, said Darvin Winick, chairman of the National Assessment Governing Board, the bipartisan panel that oversees the test.
Over time, schools have done rather well with elementary school kids, better with middle-school kids and stalled with high-school kids, Winick said.
The biggest gains came from low-achieving students. That is probably not an accident — the federal No Child Left Behind law and similar state laws have focused on improving the performance of minority and poor children, who struggle the most.
"The big pressure for the last six, eight years in this country has been on bringing the lower-performing students up," Winick said. "And what this long-term trend says is, generally, that's what's happening."
Tom Loveless, an education expert at the Brookings Institution think tank, said the progress in reading is noteworthy.
"The gains are not huge, but they're gains," he said. "Something's going on in reading. That's a good thing."
No Child Left Behind prods schools to improve test scores each year, so every student can read and do math on grade level by the year 2014. It holds schools accountable for progress among each group of kids, including those who have disabilities or are learning English.
The law was due for a rewrite in 2007, but the effort stalled in Congress. The Obama administration and Congress are gearing up now to make another attempt.
The House Education and Labor Committee chairman, Democratic Rep. George Miller of California, called it "deeply troubling" that high-school students did not show improvement.
"We must redouble our efforts to ensure that all students, at every age, in every state, get a world-class education that fully prepares them for college and careers," Miller said in a statement.
The long-term trend report issued Tuesday was based on a nationally representative sample of more than 26,000 public and private school students. It tracks student progress in reading since 1971 and in math since 1973.
Because it is aligned with older tests, the long-term trend may give a more conservative picture of how kids are doing. It is separate from the main NAEP assessments, which are given in nine subjects and have shown greater progress in math scores.