General Science:
https://www.learn4good.com/games/scienceforkids.htm
http://easyscienceforkids.com/
http://pbskids.org/games/science/
http:billnye.com/blog/
https//www.nih.gov
http://highwire.stanford.edu/lists/freeart.dtl
http://symphonyofscience.com
https:ukedchat.com/ictmagic/science/
https://www.si.edu/explore/science
https://www.sciencefriday.com/series/aha/
https://www.thetechathome.org/activities
https://help.oceanschool.nfb.ca/learn-from-home
Plants:
http://www.sciencekids.co.nz/plants.html
http://www.biology4kids.com/files/plants_main.html
Earth & Space:
https://www.nasa.gov/audience/forstudents/k-4/index.html
https://www.jpl.nasa.gov/edu/learn/
Matter:
http://www.abcya.com/states_of_matter.ht
Molecularium Project:
http://www.molecularium.com/kidsite.html
Force, Motion, & Energy:
http://engineergirl.org
Weather:
http://www.sciencekids.co.nz/
Investigation: