Sometimes students like to read their own books online or have the books read to them. Two of my favorite website that I have for my students to read books online are BookFlix and StorylineOnline. I like Bookflix because they offer the option of having readers read the text or having the text read to the reader. I also like that the books are paired with a fiction and a nonfiction book based on the same topic. I would not have known about BookFlix if I had not been a member of MACUL (Michigan Association for Computer Users in Learning) member ship is FREE. Here is the link to MACUL.
Another great free book resource for teachers to use with their students is Epic Books. I like Epic books because teachers have a dashboard that houses data. Students get to the site via a join code. Teachers can upload quizzes and assignments for students. The website has lots of books in several genres.