America's 9-year-olds and 13-year-olds are posting better scores in math and reading tests than their counterparts did 40 years ago, and the achievement gap between white students and those of color is narrowing, according to federal government data released Thursday.

The scores — collected regularly since the 1970s from federal tests administered to public and private school students age 9, 13, and 17 — paint a picture of steady student achievement that contradicts the popular notion that U.S. educational progress has stalled.

"When you break out the data over the long term and ask who is improving, the answer is . . . everyone," said Kati Haycock, president of the Education Trust, a nonprofit that works to close the achievement gap between poor and privileged children. "And the good news, given where they started, is that black and Latino children have racked up some of the biggest gains of all."