The MetaMetrics corporation has created a book difficulty measurement device, called the Lexile system. It purports to rate books based on their difficulty level—but readers who study their grading system find it faulty. Mark Mitchell at Front Porch Republic and The New Republic contributor Blaine Greteman both criticize the program, both on a practical and philosophical level. Greteman writes,

On my way to work I pass the House on Van Buren Street where Kurt Vonnegut began Slaughterhouse Five—but with a score of only 870, this book is only a fourth-grade read. By these standards Mr. Popper’s Penguins (weighing in at a respectable 910) is deemed more complex … many of the smartest and best have learned the Lexile model too well. They’ve long been rewarded for getting “the point” of language that makes “a parade of its complexity,” and they’ve not been shown that our capacity to manage ambiguity without reducing it enables us to be thinkers rather than mere ideologues. It’s this kind of thinking that makes us “humans” rather than mere “machines.”

They are right. The Lexile measure is quite faulty in its analysis of books. Oftentimes, its ratings do not make sense. But that does not mean the entire concept of the measurement is wrong. It has some limited uses that may be developed with time. Having used the program recently for report research, I have observed a few of the Lexile system’s benefits and drawbacks. It is important to note, at the outset, that Lexile doesn’t even attempt to measure the content of books. The website explains:

A Lexile text measure is based on the semantic and syntactic elements of a text. Many other factors affect the relationship between a reader and a book, including its content, the age and interests of the reader, and the design of the actual book. The Lexile text measure is a good starting point in the book-selection process, with these other factors then being considered.

Thus, the creators themselves note that the Lexile sytem is not all sufficient. It is merely a starting point. Lexile measurements will never be fully objective: they only measure the outward difficulty of things. They cannot truly measure content. Teachers who base their entire curriculum off of Lexile scores will be sorely disappointed.

That being said, the Lexile system could be a useful tool in comparing the rigor of various curricula. It most definitely should not be the sole measurement of books’ usefulness for a class, but if a teacher wants to determine which curricula might be more challenging for students, the Lexile measures offer a preliminary framework for comparing works. The Lexile system’s website has a search engine to find books’ Lexile scores. This could help parents who want to buy books for grammar-challenged kids.

Greteman says that the “Lexile scoring is the intellectual equivalent of a thermometer: perfect for cooking turkeys, but not for encouraging moral growth.” He is right. But cooking a turkey takes more than a thermometer. The ability to pick the perfect herbs, spice rub, stuffing, and condiments—the real content of a turkey’s taste—lies in the skill of a cook. They, not their tools, create a good turkey. Does this mean good cooks should throw out their thermometer? No. Any good cook will have a thermometer on hand, to test and determine the “readiness” of the bird. A thermometer can’t judge a poor or excellent turkey—but it can tell you whether the turkey is appropriately cooked for eating.

The Lexile system is, similarly, a tool: like any tool, it is insufficient. Perhaps its creators will find ways to incorporate qualitative measurements into their scoring system—but do we want them to? I don’t mind utilizing a little common sense alongside the Lexile “thermometer.” Any good teacher should know better than to believe Sports Illustrated for Kids’ Awesome Athletes is more complex than Jane Eyre.