This QuickTime movie provides an opportunity to learn about congruent/vertical angles. As you watch and listen to the teacher and student interact it helps clarify the thinking behind applying this concept.

Common Core

8.G.A.2 8.G.A.5 4.MD.C.7 4.MD.C.5.b 4.G.A.1 8.G.A.1.b 4.MD.C.5.a