Why Read Shakespeare When Clancy Can Get You a Pizza Party?

It does, she said, "intrinsically encourage" students to choose longer books because point values are higher.

Other readability formulas used by publishers and educators to measure text also use length as well as word difficulty.

Formula results can often be found on the back of books, especially paperbacks. If, for example, a book says RL: 4.2, it generally means the text is for early fourth-graders. Of course, the same book published by different publisher could have a different reading level.

Borkon said readability formulas cannot measure every important element of a book, including context or difficulty of the material. They can't even measure whether a work is coherent, according to a report on readability formulas issued by Renaissance Learning.

Lincoln's Gettysburg Address would be rated "exactly equal" on readability formulas if the exact same text were read backward, according to the report.

"Four score and seven years ago our fathers brought forth upon this continent a new nation, conceived in liberty and dedicated to the proposition that all men are created equal," would be equivalent to: "Equal created are men all that proposition the to dedicated and liberty in conceived, nation new a continent this upon forth brought fathers our ago years seven and score four."

That, Borkon said, is why the quizzes that measure comprehension are so important to Accelerated Reader. And that is why some booksellers and buyers say they don't look at reading levels.

"We don't pay attention to that a bit," said Morgan McMillian, children's department bookseller at the independent bookstore Politics and Prose in the District. "We determine where to put the books after we read them ourselves."

Award-winning author Louis Sachar said he finds readability formulas somewhat off the mark. His "Small Steps" for fourth-graders earns a reader 7 points. And "There's a Boy in the Girls' Bathroom" earns third-graders 5 points.

Sachar, who has written more than 20 fiction and educational books, said he was surprised that "Small Steps" was targeted by Accelerated Reader for fourth-graders because he believes it is well-received by children from fourth through eighth grade.

Told that Accelerated Reader had assigned "Small Steps" one more point than "Macbeth," he said: "They have a strange formula. Obviously it takes a lot more work to read Shakespeare than it takes to read my books."