Younger students have regained ground academically after the pandemic's disruptions, while older students' test scores continue to stagnate, according to the latest testing data released by the federal government.

Nine-year-olds rebounded to pre-pandemic reading scores and saw some recovery in math, according to data from a test taken regularly in the U.S. since the 1970s.

The same recovery has not emerged for 13-year-olds, whose average scores in math and reading remain below pre-pandemic averages.