https://unctv.pbslearningmedia.org/collection/btl07-ex/    good site for K-2

https://www.starfall.com/h/  K-3 

https://ell.brainpop.com/

https://www.readingbear.org/​

https://www.funbrain.com/ K-8 reading and math learning games

http://www.esl-kids.com/eslgames/eslgames.html  not online games, but lots of ideas for games to play in class or at home to practice English

http://www.eslgamesworld.com/members/games/levels/  upper elementary - advanced/high school

Other fun apps/sites for elementary age children;  www.cookie.com, www.peppapig.com,