Virginia's fourth- and eighth-graders perform better in reading and mathematics than their peers nationwide. But less than two-fifths have a solid grasp of reading and less than half have a solid grasp of math.

The National Assessment of Educational Progress results released Tuesday show 36 percent of public school eighth-graders achieved "proficient" reading scores in 2011, up slightly from 32 percent in 2009.

Among fourth-graders, 39 percent achieved proficient scores, compared to 38 percent in 2009.

In math, 40 percent of eighth-graders achieved "proficient" scores in 2011, up from 36 percent in 2009. Forty-six percent of fourth-graders performed at the proficient level, compared to 43 percent in 2009.

The tests, also known as "the nation's report card," are considered the best gauge of public schools' student performance in core subjects.