By KIMBERLY HEFLING

AP Education Writer

WASHINGTON (AP) _ Handing out dismal grades, the Nation’s Report Card says America’s high school seniors lack critical math and reading skills for an increasingly competitive global economy.

Only about one-quarter are performing proficiently or better in math and just 4 in 10 in reading. And they’re not improving, the report says, reinforcing concerns that large numbers of today’s students are unprepared for either college or the workplace.

Scores on the 2013 exam in both subjects were little changed from 2009, when the National Assessment of Educational Progress was last given to 12th-graders. The new results, released Wednesday, come from a representative sample of 92,000 public and private school students.

The report follows the just-released and seemingly more encouraging research that U.S. high school graduation rates in 2012 reached 80 percent, a record.

One possible explanation is that lower-performing students who in the past would have dropped out of school are now remaining in the sampling of students who take the exam, said John Easton, acting commissioner of the Education’s Department’s National Center for Education Statistics.

Wednesday’s results are likely to embolden supporters of the Common Core standards that are being rolled out in 44 states and the District of Columbia. Designed to develop critical thinking skills, they spell out what math and English skills students should master at each grade.

There have been political storms in many states over the standards, which were pushed by governors who were concerned about the skill levels of their high school graduates. Opponents say the standards have a federalist bent and are untested.

Bob Wise, president of the Alliance for Excellent Education and a former governor of West Virginia, said the new national results speak to a “desperate need for the aggressive implementation” of the standards.

In reading, the 38 percent share of students performing at or above the proficient level was lower than when the assessment was first given in 1992, when it was 40 percent. Scores have remained similar since 1994.

Past comparisons in math date only to 2005. Scores had increased from 2005 to 2009.

Student participants’ responses to a survey about their educational experiences offered some clues about their performance.

Among the findings:

_Students who reported rarely or never discussing reading interpretations in class averaged lower scores than those who had such discussions daily or almost daily.

_An overwhelming majority reported that reading was enjoyable. Students who strongly disagreed with that idea had scores much lower than those who strongly agreed.

_Math scores were higher, on average, for students who took calculus and lowest for students who had not taken a math course beyond Algebra I.

_Math scores were higher for students who reported math was their favorite subject, believed it would help them in the future or thought their class was engaging.

Even as 12th-grade scores have stagnated, fourth- and eighth-grade students have made slow but steady progress on the exam since the early 1990s; most progress has come in math.

Michael Petrilli, executive vice president at the Thomas B. Fordham Institute, said it’s unclear why younger students are doing better while high school seniors are not.

“This is one of the great mysteries of education today is why are we not seeing the same improvements at the 12th-grade level as the fourth- and eighth-grade level,” Petrilli said.

One speculation is that high school seniors simply aren’t motivated when they take this exam. More ominously, another thought is that students are taking watered-down classes and “all we’ve done is put them in courses with bigger titles,” said Mark Schneider, the vice president at the American Institutes for Research. He is the former commissioner of the National Center for Education Statistics.

At all levels, there continue to be racial disparities.

Among high school seniors, white and Asian students scored higher on average in the recent results in both reading and math than black, Hispanic and American Indian students. Asian students scored higher than white students in math but did not do significantly better in reading. As in past years, male students did better than female students in math, but females outperformed males in reading.

The new results did not include global comparisons, but U.S. students historically do poorly on international assessments compared to many foreign peers.

Education Secretary Arne Duncan noted that despite the good news related to graduation rates and scores in younger grades, high school achievement has been flat in recent years.

“We must reject educational stagnation in our high schools, and as a nation we must do better for all students, especially for African-American and Latino students,” Duncan said in a statement.

Community colleges and four-year institutions have been trying to improve their remedial education programs, given that only about one-quarter of students who take remedial classes end up graduating.

It’s estimated that more than one-third of all college students, and more than one-half in community colleges, need some remedial help, according to research from the Community College Research Center at Teachers College, Columbia University.

In addition to the national scores released Wednesday, 13 states voluntarily participated at a greater level and had scores reported.