Some titles in your school or library's digital collection may display standardized reading level information, including interest level, ATOS level, Lexile measure, and/or text difficulty. These levels are calculated by third party evaluators to help readers decide which titles are right for them.
Please note that your school or library may choose not to display certain standardized reading levels. Additionally, not all titles have been scored for all standardized reading levels.
Interest level indicates the age-appropriateness of a title's content. This score is unrelated to reading difficulty. Interest level may be one of four values: LG (Lower Grades, K-3), MG (Middle Grades, 4-8), MG+ (Upper Middle Grades, 6 and up), or UG (Upper Grades, 9-12). Scores are determined by Renaissance Learning, Inc., as a part of their Accelerated Reader program. For more information, see the Parent's Guide to Accelerated Reader.
ATOS level indicates how difficult a book is to read based on the ATOS readability formula, which evaluates the number of words per sentence, the number of characters in each word, and the difficulty of the words. ATOS levels are determined by Renaissance Learning, Inc., as a part of their Accelerated Reader program. For more information, see the Parent's Guide to Accelerated Reader. For an approximate correlation between ATOS levels and grade levels, see Learn More about Using the Accelerated Reader College and Career Readiness Report.
Lexile measure indicates how difficult a book is to read based on word frequency and sentence length. Lexile measures are reported by MetaMetrics. For more information, including an approximate correlation between Lexile measures and grade levels, see Lexile-to-Grade Correspondence.
Text difficulty scores are created by OverDrive, Inc. and are based (where available) on a weighted average of the ATOS level and Lexile scores' grade equivalents, as presented in literature from the National Governors Association Center for Best Practices and the Council of Chief State School Officers. Text difficulty scores are presented as a range of grades (U.S.) or school years (international). This score does not address the age-appropriateness of a title.