Maryland's elementary and middle school students continued to make gains on last year's round of state tests in reading and math, according to a report released Wednesday by the nonprofit Center on Education Policy in Washington, D.C.

The nonprofit group, a national independent advocate for public education, analyzed test scores over the past six years from all 50 states. The report focused on improvements in test scores since 2002, the year the federal No Child Left Behind Act was signed into law.

Under the act, the states are allowed to choose their own test to assess student progress.

Each spring, the state gives the Maryland School Assessments in reading and math to all third- through eighth-graders.

The biggest increases came on the seventh-grade MSAs in reading and math.

Last year, 81 percent of the state's seventh-grade students scored at least proficient on the MSA in reading, compared with 70 percent the year before, according to the report. The MSA is scored based on three levels: basic, proficient and advanced. Basic is the lowest level, while advanced is the highest.

Some 68 percent of the state's seventh-grade students scored proficient on last year's MSA in math, compared with 61 percent the year prior, the data show.

Ronald A. Peiffer, the state Department of Education's deputy superintendent for academic policy, attributed the middle school gains to a statewide curriculum that all school systems must follow.

"We've been very transparent and clear with school systems on what ought to be taught and what ought to be tested," Peiffer said Wednesday.

Fifth-grade students also made significant gains on the reading MSA. Last year, 87 percent of those students scored proficient or above, compared with 77 percent the year before.

The state also saw increases in the percentage of students who scored advanced on the MSAs. In 2008, for instance, 34 percent of eighth-graders scored advanced on the reading MSA, compared with 24 percent who scored advanced the year before.

In the report, the Center on Education Policy also noted that achievement in high schools has improved, but still lags behind elementary and middle school gains.

Researchers found that the annual percentage point gains for high school students were lower than the gains in elementary and middle schools.