Washington (CNN) -- A national assessment of students' grasp of science at three grade levels found that only 34% of the fourth-graders, 30% of the eighth-graders and 21% of the 12th-graders qualify as proficient.

The National Assessment of Education Progress places students in one of three tiers: basic, proficient or advanced. At a proficient level, students show competency over challenging subject matter at their grade level.

The periodic NAEP reports normally measure trends in academic achievement of U.S. students, but changes in the 2009 assessment to account for updates in science mean the latest report cannot be used as a comparison to previous ones. The 2009 report will be used as a baseline for future comparisons.

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The report shows that only 1% of fourth- and 12th-graders reached the advanced level, while 2% of eighth-graders made that level.

"When only one or two percent of children score at the advanced levels on NAEP, the next generation will not be ready to be world-class inventors, doctors and engineers," said Education Secretary Arne Duncan in response to the report.

"Our nation's students aren't learning at a rate that will maintain America's role as an international leader in the sciences," he said.

The report says fourth-graders in New Hampshire, North Dakota and Virginia had the highest average scores by state. Eighth-graders in Montana and North Dakota had the highest average scores for that grade. Males scored higher than females in all grades.

The full report can be found at www.nationsreportcard.gov.