NOVA’s program The Elegant Universe has an excellent website where the entire three hour video is available for free (with a full screen option). They have also broken the video up into segments and have a great teachers’ page which summarizes what’s in each segment.
Created in 2003, when string theory was making it’s big splash in the popular consciousness, The Elegant Universe starts with Newton’s observations of gravity, shows Einstein’s separate explanations of why gravity works and the nature of the sub-atomic world, and finally delves into string theory which tries to reconcile Einstein’s two theories into a unified whole.
We don’t usually get past Newton in middle school, but this PBS program introduces such a wider and weirder view of the universe that it can help strike the imagination. It also presents complex concepts in an intelligible way.