Epic!

https://www.getepic.com/

 

Digital Book.io

https://www.digitalbook.io/

 

Storyline Online

http://www.storylineonline.net/

 

Starfall

http://starfall.com/

 

International Children's Digital Library

http://en.childrenslibrary.org/

 

ABCya!

http://www.abcya.com/

 

Storynory

http://www.storynory.com/

 

National Geographic Young Explorer

http://ngexplorer.cengage.com/ngyoungexplorer/index.html