The Lexile Framework for Reading

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Why do some books receive updated Lexile measures?

Last Updated: Jun 07, 2017 05:23PM EDT
With the new enhancements, the text complexity of a book or piece of text written in the typical range of K–2 books (i.e. 650L and below) is now being measured across more dimensions. As a result, more text features are being evaluated in order to determine the Lexile measure. Because the process for providing a Lexile text measure has been enhanced, a subset of previously published materials may require an updated Lexile measure. If a book receives a lower Lexile measure, it may have previously unmeasured text features such as easy-to-decode words or patterning and repetition that can provide important supports for beginning readers as they tackle texts on their own or with minimal assistance. Conversely, if a text receives a higher Lexile measure, it may have relatively short sentences along with harder-to-decode, less familiar or more abstract words, and lack supports related to patterning and repetition. Please keep in mind that the majority of books were not impacted.
While making new enhancements to more precisely measure content in the early grades, we also incorporated additional improvements to better measure all content, regardless of its placement on the Lexile scale. The corpus that is used to determine the semantic demand (word difficulty) now contains over 1.4 billion words, which is almost triple the number of words it previously contained. British spellings were also updated to allow for better measurement of the text complexity of materials that are read in the United Kingdom and other countries that use British English. These updates improve the measurement of all materials.

For more information on these enhancements and matching beginning readers with texts, visit
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