Kid Citizen is a free site designed for students to learn with primary sources.
It says its focus is K-5, but I think it could be useful with older students, too, – particularly English Language Learners.
It’s filled with interactive videos and, on top of that, teachers can also create their own interactives, share them with students, and monitor student progress through a sort of virtual classroom.
I’m adding it to:
The Best Resources For Using Primary Sources
The Best Sites Where Students Can Work Independently & Let Teachers Check On Progress