Here are a ton of online STEM resources available for kids:

https://code.org/learn

https://www.techrocket.com/

https://spaceplace.nasa.gov/

https://www.usa.gov/education?source=kids

https://www.funology.com/

https://www.tynker.com/

https://www.nasa.gov/audience/forstudents/index.html

https://science.howstuffworks.com/

Science Website for Kids