NPR had an eye-opening story related to this last week about the anniversary of the Tiananmen Square uprisings. There were young Chinese who either did not believe it really happened or didn't believe their government would have committed acts of violence against its own people unprovoked.
This was attributed to the lack of accurate, information inside China about the event that hadn't been "sanitized" by government censors. It's not even mentioned in history classes! Amazing.