I used The Enigma of Kaspar Hauser, by Werner Herzog, on big sister a few years back. Big sister is now seven years old. She was compelled by this story of a man who didn't know language as an adult because he'd been raised away from any meaningful human contact.
What touched big sister was a scene where children her age were teaching Kaspar, a grown man, how to speak. They shared a kitten with him and used sign language. Big sister's reading skills weren't quite as fast as the subtitles to the film, but she didn't seem to mind the German. She still asks about that movie.
Several scenes weren't appropriate for a kid. It's so much better for her than Hanna Montana, which we're having a difficult time escaping.