Here is another great resource to read/listen to books online. There are 3 different databases to choose from.
www.TumbleBookLibrary.com - K-6 children's ebook database
Direct Link: https://www.tumblebooklibrary.
www.TumbleMath.com - K-6 math ebook database
Direct Link: https://www.tumblemath.com/
www.AudioBookCloud.com - This site is an audio book database for kids to adults, however the direct link below provides direct access to the children's section.
Direct Link: http://www.audiobookcloud.com/