WASHINGTON — A report on student testing released Thursday finds big gaps in most states between the percentage of students shown to be proficient in reading and math on state tests and the much lower number found to be proficient on a national benchmark test.

Dozens of states showed significant gaps between their state tests in the 2013-14 school year and the results of the National Assessment of Educational Progress on tests of reading and math in fourth and eighth grades.

The picture is expected to change in upcoming years because many states have raised their academic standards and started using new tests to measure them this year. Results will be available in the fall.

“Too many states are not leveling with students or parents. They’re being told students are proficient, but by external benchmarks they’re not prepared at all,” said Michael Cohen, the president of Achieve, the education reform group that conducted the survey. Cohen added improvements are expected.

Achieve helped the National Governors Association and the Council of Chief State School Officers develop the Common Core, the standards that define what students should know and be able to do.

Many states adopted new tests to measure the new standards. Cohen called it a “multiyear, multistate effort to raise expectations.”

Georgia, for example, began its new Georgia Milestone tests this year. The state had some of the biggest gaps that Achieve found on last year’s tests: 60 percent more scoring proficient in fourth-grade reading on the state test than on national assessment; a 43 percent gap on fourth-grade math; a 65 percent gap on eighth-grade reading; and a 53 percent gap on eighth-grade math.

The National Assessment of Educational Progress is the only consistently used national measure of all students. It is given every other year to a sample population.