U.S. students knew only about half of what they were expected to on a new vocabulary section of a national exam [NAEP], in the latest evidence of severe shortcomings in the nation’s reading education.

Eighth-graders scored an average of 265 out of 500 in vocabulary on the 2011 National Assessment of Educational Progress, the results of which were made public Thursday. Fourth-graders averaged a score of 218 out of 500.

The results showed that nearly half of eighth-graders didn’t know that “permeates” means to “spread all the way through,” and about the same proportion of fourth-graders didn’t know that “puzzled” means confused—words that educators think students in those grades should recognize…

African-American and Latino students posted scores lower than white and Asian students at every grade level. Low-income students scored far below their wealthier counterparts. The gaps between the groups ranged from 28 to 31 points.

From today’s Wall Street Journal, which notes that a new vocabulary section was embedded in the NAEP (National Assessment of Educational Progress) reading section for the first time in 2009, but this year’s results are the first to be made public.