The film Imagining America: Icons of 20th Century American Art originally was broadcast on public television in 2005. Recently it became available on the Chicago Humanities Festival Website. It's an excellent introduction to three themes: how artists respond to place, how art is used to reinvent or reimagine personal and national identity, and what art helps us to understand about our social history and popular culture. The first segment is embedded below; you'll find the others here. (The segments are of a length that you may watch as your time allows.)
A section of the site includes two Lesson Plans for teachers of art history, history, and English: "Art and Environment: Exploring the Connection Between Art and Nature" and "Art and Technology: Navigating the Intersection of Two Great Forms".