TumbleBooks is a pay-for-use site that traditionally sells licenses to libraries and schools.  Many public libraries, such as the Tell City, IN Public Library, offer free access to their TumbleBooks account.  Students can follow along as the text is read them to help improve comprehension and fluency.  Choose from picture books to chapter books.  Portland Public Library also has free access to TumbleBookCloud which gives access to Middle and High School level books.  If your school decides to purchase a school license, there is also access to the Common Core Portal that includes lessons and quizzes to accompany the books.