https://www.kiddle.co/
https://www.dkfindout.com/us/
http://www.britannica.com/
http://childrenslibrary.org   (large variety of books available in English and other languages)
https://kids.nationalgeographic.com/
https://jr.brainpop.com/
https://kids.wordsmyth.net/we/  kid's dictionary
https://kids.wordsmyth.net/wild/#/home  picture dictionary for K-3
​https://www.sldirectory.com/virtual.html  The Virtual Middle School Library