I keep seeing this and it's not clear to me if this is general literacy or specifically English literacy. 21% of USAmericans speak English as a second language (or specifically "a language other than English at home"), which has to weigh on these statistics right?
Not enough to explain it away. Even if every single one of them were counted that's still a large number of English-as-a-first-language speakers who are reading below a 6th grade level. It just seems like something that's important to consider.
