WASHINGTON — The nation's 9-year-olds last year posted their best scores in reading and math in more than three decades, according to a study released yesterday.

At the same time, achievement gaps between racial groups narrowed, according to results of the 2004 National Assessment of Educational Progress.

The Bush administration seized on the data from the widely respected assessment as evidence that its educational reforms are working.

"These results show that when performance is measured, and schools are held accountable, every child can succeed," President Bush said during an appearance yesterday at a black business convention in Indianapolis.

But the independent body that administers the tests urged caution, saying that much of the improvement could have come from reforms instituted before the passage of the 2002 No Child Left Behind Act.

On last year's National Assessment, sometimes known as the nation's report card, 9-year-olds earned their highest scores since the tests were first given: 1971 for reading and 1973 for math.

The exams are given periodically to 9-, 13- and 17-year-olds. The most recent previous tests were given in 1999.

On a scale of 0-500, the 9-year-olds scored 219 in reading in 2004, compared with 212 in 1999 and 208 in 1971. In math, they scored 241 last year, compared with 232 in 1999 and 219 in 1973.

The message is "that persistence pays off," said Francie Alexander, a member of the National Assessment Governing Board, which oversees the test.

Results were mixed for 13-year-olds, and remained flat for 17-year-olds.

Thirteen-year-olds earned their highest math scores ever, but their reading scores were just a few points better than in 1971 and about the same as five years ago.

In math, their average scores went from 255 in 1973 to 276 in 1999 and a high of 281 in 2004. In reading, the trend was 255 in 1971, rising to 259 in 1999 and holding at that level in 2004.

Seventeen-year-olds continued a trend of flat scores in both subjects, although greater percentages reported taking advanced math, such as second-year algebra or calculus.

Their reading score of 285 was the same in 1971 and 2004, while it was 282 in 1999. Math scores increased from 304 in 1973 to 308 in 1999 before falling back to 307 in 2004.

Charles Smith, executive director of the assessment governing board, attributed that performance to the traditional slacking off by high-school seniors.

"The problem with senioritis is alive and well," he told AP Radio.

Among racial groups, most gaps in reading and math scores narrowed. Every age group, except for Hispanic 13-year-olds, cut into the achievement gap with whites in comparison with the 1970s.

In reading, black and Hispanic students scored higher than in the early 1970s, with 9-year-olds in both groups posting their best scores yet, 200 and 205 points respectively.

In math, minority students scored higher than in the 1970s, with 9- and 13-year-olds in both groups earning their highest marks in the history of the exam. Among blacks, the scores were 224 and 262, respectively; among Hispanics, they were 230 and 265, respectively.

Only black and Hispanic 17-year-olds showed no improvement from five years earlier. All age groups, except for Hispanic 9-year-olds, have narrowed the achievement gap since the 1970s.