This PowerPoint presentation, a collaboration between me and Ji Hye Lee, activates students’ prior knowledge about angles in the real world and angle relationships.
The video tutorial from this PowerPoint presentation demonstrates how the measure of <DEH is found by reviewing the relationship of supplementary angles and how a missing angle can be found within a triangle if two other angles are known. The video uses the GeoGebra tool to highlight angle relationships. Originally recorded with Screen-cast-omatic, the link is currently unavailable.
The following standards are addressed:
- CCSS.Math.Content.7.G.B.5 Use facts about supplementary, complementary, vertical, and adjacent angles in a multi-step problem to write and solve simple equations for an unknown angle in a figure.
- CCSS.Math.Content.8.G.A.5 Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.