Lexile Leveling: The Buford Senior Academy Media Center is Lexile based. Lexile measures the complexity of the text by breaking down the entire piece and studying its characteristics, such as sentence length and word frequency, which represent the challenges of the text. Vocabulary, text structures, and readability are also accounted for when determining the level. All books are measured using this guide, but all books are different, even in the same series or with the same author. Nonfiction books, fiction books, and picture books are not compared side by side, but instead through these characteristics. Some books may be shorter or longer, but length is not the determining factor.