I shared a few Google Apps with the kids in 3PA today, and they asked that I pass them on.
The free BioDigital Human App gives a 3D view of different systems in the human body and has loads of information about different medical conditions.
https://www.biodigital.com/education
Readability is an app that will remove all ads, videos, and links on any website the kids want to read information on, like Ancient Egypt. I use this at school all the time. It will appear as a red chair on your Google Chrome browser, just click on "read now" to filter out all the extra stuff.
https://www.readability.com/
Epic, is, well epic!!! It's an online library with thousands of books. It's free for educators, but for at home use there is a fee. It's pretty amazing.
https://www.getepic.com/app/