The University of Tennessee- Knoxville has a website that contains a series of animated presentations that describe some fundamental principles of computer science. There are modules there that describe:
These are resources one could easily assign students to view on their own during a study hall or other time when the regular computer teacher is missing but you still want kids to actually learn something. Or they could be used as a regular part of a class in computer history or computer literacy. Actually I can think of a lot of times and courses that could benefit from these modules. In fact I may send this link to some adult members of my family so I don't have to explain these principles to them myself.
These materials are very well done. Get to them at http://www.cs.utk.edu/modules/