Seriously, say what you will about the monster, but he was a fantastically ingenious leader. Dubya couldn't lead a dog to a bowl of kibble.
Hitler ruled through fear and intimidation. He motivated people with the threat of violence, not with actual rhetoric. He is one of history greatest bullies, and was not a particularly effective leader except to know to secure the control of the police and military in his power grab.
It doesn't seem to be too big of a deal. I can compare anything to anything and find similarities. It is a pretty basic exercise in logical thinking, only the subject matter is kind of weird. I am not sure if 12 year olds need to know in depth the stuff that Hitler did, or if they did that they would know a fairly sanitized version which doesn't do justice to his evil.