Why are US dollars no longer backed by gold and silver? What is our medium of exchange, and what would it be like to live in a barter economy? Learners consider these questions, as well as learn about the major historical events in the...

This is not revolutionary, but it is informative. Earth science viewers in grades 7-12 get carried away with wave and wind erosion. They view diagrams of how waves impact ocean shorelines. They see examples of the different types of sand...