Arguing that teachers aren't assigning grade-appropriate reading, Common Core recommends that students get matched up with books with the right "Lexile" score. The thing is, Lexiles measure a book's complexity by a painfully literal algorithm of sentence length, word choice, and syntax.

To be fair, it's only meant to be a rough guideline rather than some iron-clad dictum or curriculum. And any teacher knows that a work can have a low Lexile difficulty while being thematically unsuitable for younger readers. But still.