Since they’ve been incorporated into the Common Core documentation, Lexile scores are being printed on more and more children’s books as a supposedly value-free method of indicating reading level. As the Lexile website says “In order to Lexile a book or article, text is split into 125-word slices. Each slice is compared to the nearly 600-million word Lexile corpus – taken from a variety of sources and genres – and words in each sentence are counted. The sentence length and difficulty of the vocabulary is examined throughout the book. These calculations are put into the Lexile equation. Then, each slice’s resulting Lexile measure is applied to the Rasch psychometric model to determine the Lexile measure for the entire text.” (The use of “Lexile” as a verb perhaps reduces one’s confidence in the ability of these guys to adjudicate on reading.)

The difficulty of a book may not just be down to its sentence length and vocabulary, which is what Lexile measure, though they are quite up-front about this. The Digital Reader calls the whole thing into question because of some admittedly fairly surprising results. Still a guide is just a guide. There may be features other than Lexile score which might lead a teacher to assign To Kill a Mockingbird over Mr Popper’s Penguins.


I suppose this is all valuable in some sort of way. Standardizing our assessment tools is a laudable aim. But I can’t buck the feeling that a teacher, a parent, a friend, reading with a child will be liable to know just as much about that child’s reading abilities as any amount of scientific-looking analysis can tell them. On an idiot level: if you only read stuff Lexile tells you you can read, how do you ever progress to reading something more complicated? Struggling with unfamiliar vocabulary is something we all cope with, regardless of our age and experience. Still, we live in an age where having teachers think for themselves is seen as a danger: we appear to need to control everything.