Recently I learned about Zing, an app with free books, by Schoolwide Inc. I created a class account which my students joined.
Right now I am using the free account. This week all my students read a book about bridges prior to a bridge building challenge and they read about sound prior to a series of sound and vibration experiments. As they read Zing gives students the opportunity to take notes and highlight within books and it has a dictionary feature.
There are 1000s of free books I can add to the class library for students to read. I can browse by topic/category as well as reading level. Some books have quizzes associated with them. There's a good mix of fiction and non-fiction books to choose from.
I plan to use Zing throughout the year in combination with Epic to provide my students with a varied set of books on different topics of interest at a wide range of reading levels.