• Q: What does the Lexile® measure mean?

    There are two Lexile measures: the reader measure and the text measure. They each have a separate, though related meaning. When used together, they can help a reader choose a book that is at an appropriate difficulty level. The Lexile reader measure can also be used to monitor a reader’s growth in reading ability over time.

    The Lexile reader measure tells where a person’s reading ability is on the Lexile scale. Reader measures are reported from 0L (0 Lexiles) to 2000L (2000 Lexiles). The Lexile scale is a scale for reporting reading ability, so a higher number means a higher level of reading ability. A reader measure is usually obtained by having the reader take a test of reading comprehension. The reader’s score on the test is reported as a Lexile measure. Readers who score below 0L receive a score of BR (Beginning Reader). 

    The Lexile text measure tells where a book’s readability is on the Lexile scale. Text measures, like reader measures, are reported from 0L (0 Lexiles) to 2000L (2000 Lexiles). Scores below 0L are reported as BR, which indicates that the text is at a level appropriate for a Beginning Reader. The lower a book’s Lexile measure, the easier it will likely be to comprehend. For example, a text with a Lexile measure of 850L will most likely be easier for a reader to comprehend than a text with a 950L measure.

    It is important to note that the Lexile measure of a book refers to its text difficulty only. A Lexile measure does not address the content or quality of the book. Lexile measures are based on two well-established predictors of how difficult a text is to comprehend: word frequency and sentence length. 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 measure is a good starting point in your book-selection process, but you should always consider these other factors when making a decision about which book to choose. A very useful feature of the Lexile reader and text measures is that they can be used to predict how well a reader will comprehend a text that has a Lexile measure. For example, if a reader has a Lexile measure of 600L (600 Lexiles) he will be forecasted to comprehend approximately 75 % of a book with the same Lexile measure (600L).

    When the Lexile measures and the Lexile scale were developed, the 75% comprehension rate was set at the point where the difference between the reader measure and the text measure is 0L. The 75% comprehension rate is called “targeted” reading. This rate is based on independent reading; if the reader receives help, the comprehension rate will increase. The target reading rate is the point at which a reader will comprehend enough to understand the text, but will also face some reading challenges. At this point, a reader is not bored by text that is too easy, but also does not experience too much difficulty in understanding. In some cases, you may not want to choose a book at the 75% forecasted comprehension rate.

    When choosing books, it is best to consider a range of Lexile measures rather than only focusing on the one reader measure. At MetaMetrics, Inc. we refer to a “Lexile Range” as the suggested range of Lexiles that a reader should be reading. The Lexile Range for a reader is 50L above their Lexile measure to 100L below. This range takes into account measurement error found in the tests and in the measure of the books. If a student attempts material above their Lexile Range, the level of challenge may be too great for the student to be able to construct very much meaning from the text when reading independently. Likewise, material below the reader’s Lexile Range may provide that student with little comprehension challenge. Material above or below the reader’s Lexile Range can be used for specific instructional purposes.

    One of the most important features of the Lexile scale is that it is a developmental scale. This means that it can be used to show whether a reader’s reading ability is growing (or developing) over different grade levels. For example, a student may take a test in third grade that reports a Lexile measure. If the student takes a test in a later grade that also reports Lexile measures, she can see whether her reading ability has grown. This feature allows educators and parents to monitor a reader’s growth over time. If a student’s reading growth slows down too much or even stalls, in may be necessary to provide supplemental reading instruction.

    To find the Lexile measures for books, go towww.Lexile.com/booksearch.