State-funded databases:
Britannica School https://school.eb.com
An online encyclopedia; highly recommended for research on famous people/historical figures, endangered animals, etc.; includes Elementary, Middle School, and High School levels.
ProQuest https://www.proquest.com/libraries/schools/
A collection of resources, most of which are for high school students and older. The ProQuest resources recommended for elementary students are these:
SIRS Discoverer (grades 1-9)
https://explore.proquest.com/sirsdiscoverer/home?accountid=194034
CultureGrams (grades 3-12)
https://online.culturegrams.com/kids/
TeachingBooks.net https://www.teachingbooks.net
A vast array of study guides, author interviews, book trailers, and more; searchable by grade, genre, and many other criteria.