CK-12 Foundation
Indirect Proofs in Algebra and Geometry: Lesson
Indirectly, it is a good proof method. A segment of a playlist on geometry introduces a way to prove geometric and algebraic statements. Using a general examples, the video shows how to develop an indirect proof.
Loyola University Chicago
Math Flix: Pythagorean Theorem Puzzle
This QuickTime movie uses a tangram-like puzzle to help understand the Pythagorean Theorem. As you watch and listen to the teacher and student interact it helps clarify the thinking behind applying this concept.