Wonderopolis is …
“a place where natural curiosity and imagination lead to exploration and discovery in learners of all ages.”
Lots of things to do on this site. There is a Wonder of the Day section and an Explore section.
You can watch videos.
You can read articles, and if you hover your cursor over the vocabulary underlined in orange, you can see the word definitions. You can also listen to the text (computer generated voice).
You can quiz yourself on the key vocabulary of the articles:
You can quiz yourself on the content:
And much more…