I taught high school English for almost forty years. Here is what is wrong with the whole Lexile model.
Sophisticated readers acquire their advanced reading skills through wide, avid reading. There is no shortcut. And avid readers become avid readers when they fall in love with books, and figure out how to find that next book they will love. I think it was Katha Pollitt who first used the term “independent reading life.” The best readers I had in my English classes were always, always, the kids with an independent reading life.
Children don’t develop an independent reading life when someone is always handing them a book and telling them to read it. First of all, the odds are great that the student simply won’t read the assigned book. At least half of my students told me, over and over again, both to my face and in anonymous surveys, that they almost never did all of the assigned reading. Some kids did none of it. There are all kinds of ways to avoid assigned reading, and my students knew all of them.
Secondly, when you are always just handing a book to a kid and saying “Read this,” he doesn’t develop the interest or ability to find books himself—crucial for developing advanced reading skills.
You want to raise reading scores? Open up classrooms to student-selected reading. Help students find out what kinds of books they enjoy. Allow time in class for silent reading. Reward kids who read a lot.