Actually I wouldn't espouse flipping the entire class as any format done too much gets old, BUT Keith Hughes has a video for every portion of US history and has been chosen by the Kahn Academy as a finalist for the YouTube Next EDU Guru award. Most are all ten minutes and under and feature interesting backgrounds and great ways to remember (dance moves is one of them) to remember them, but I wish he did more visual than himself. But if you want to save the time making your own flipped videos and want an extremely interesting teacher go no further than his complete Youtube library. You can follow Hughes on Twitter here. Thanks to colleague Rich Hoppock for this find.