For the first time in 25 years, 2 indicators of success have dropped for some students in the US

The National Assessment of Educational Progress (NAEP) released the results of "The Nation's Report Card" in mathematics on Wednesday, The New York Times reported.

For the first time since the test was administered in 1990, scores have dropped for the nation's fourth- and eighth-graders.

The results show that 40% of students scored at or above proficient in the fourth grade and 33% scored at or above proficient in the eighth grade.

By comparison, the previous year 42% of students scored at or above proficient in the fourth grade and 36% scored at or above proficient in the eighth grade.

Reading grades were not much better: flat for fourth-graders and lower for eighth-graders. Thirty-six percent of fourth-graders were at or above the proficient level in reading, about the same as 2013. Only 34% of eighth-grade students were proficient or better in reading, a two-point drop.

The tests were given to about 279,000 fourth-graders and 273,000 eighth-graders in all 50 states and the District of Columbia.

"It's obviously bad news," Michael J. Petrilli, the president of the Thomas B. Fordham Institute, told the Times.

"That doesn't mean we should completely freak out," he added. "But if it were the beginning of a new trend, it would be quite disappointing and disturbing."

NAEP is administered by the National Center on Education Statistics and the US Department of Education. As the largest nationally administered exam in a number of key subjects - including math, reading, history, science - it's a highly informative tool to track to progress of the nation's students towards increasing proficiency.

The results of the exam show there is clearly much more work to be done to ensure American students receive a quality education. Below is a table that shows the percentage of students, broken out by sub-groups, who score at or above proficient.

While it's difficult to attribute the fall in test scores to one particular cause, critics of the Common Core may use the results as ammunition in their fight against the controversial education standards.

"Although NAEP and the SAT were not designed to align to the Common Core, they measure what the Common Core Standards were supposed to improve -the literacy and numeracy of our nation's students," Carol Burris, an award-winning principal at a New York high school, wrote in the Washington Post.

"Considering the billions of dollars spent on these reforms, one would expect at least some payoff by now," Burris added.

The American Federation of Teachers (AFT) put its criticism even more bluntly.

"Not only is there plenty of anecdotal evidence that our kids have suffered, these latest NAEP scores again show that the strategy of testing and sanctioning, coupled with austerity, does not work," Randi Weingarten, President of AFT, said in a statement.