Talk to a librarian and find out what research databases are available there. It's likely that they subscribe to some at many different levels, including some that would be accessible at her age.
I'd let her own the inquiry, using the librarian for instruction in searching out material. You might want to teach basic note-taking and citation skills by example, because it's what real authors do as they assemble a non-fiction work, but then let her decide how to use those tools. Notecards are still awesome.
My very sensitive kids (who still have trouble watching most movies) have proven to be OK censors for themselves. DS11 will ask me very sensitive questions about Syria and the Crimea, and listen seriously to the answers, and eventually say "that's enough, that's all I want to know now, thanks." My kids knew their limits on content even at age 7 and put down books if it got too upsetting. I'm finding that I don't need to restrict reading material, though I do need to be on hand to process if they read something tough. YMMV.
