An excellent source for a variety of topics and subjects for kids - free subscriptions
https://swingeducation.com/resources/education-companies-offering-free-subscriptions-and-content-online/
Scholastic Learn at Home
https://classroommagazines.scholastic.com/support/learnathome.html
Khan Academy
khanacademy.org
Hour of Code - online coding activities that can be filtered by age and device
Code.org
National Geographic Kids
https://swingeducation.com/resources/education-companies-offering-free-subscriptions-and-content-online/
How Stuff Works
https://www.howstuffworks.com/
Fun Brain - fun for their growing brains
https://www.funbrain.com/
Museum in San Francisco
https://www.exploratorium.edu/
BBC Kids HIstory
https://www.bbc.co.uk/history/forkids/
Time for Kids
https://www.timeforkids.com/