Research
Kiddle.co
Kid version of Google. More extensive.
https://kids.nationalgeographic.com/
National Geographic Kids
DuckDuckGo
GoGooligans
https://www.lures.info/childrens_search/gogooligans.html
KidRex
SafeSearchKids
Kidzsearch.com
Britannica:
https://school.eb.com/levels
Common Sense Media
(K-5) Common Sense Media K-5