Geometers explore symmetries of isosceles triangles by using rigid transformations of the plane. They complete four tasks, including congruence proofs, which illustrate the relationship between congruence and rigid transformations. The...

How does the color of the sky change from blue to reds and oranges to black? An illuminating lesson explains how light travels through different mediums using the sun's light as an example. By examining diagrams and illustrations, pupils...

Learners investigate the symmetries of a convex quadrilateral in a collaborative activity. Rigid motion and complements are explored as learners analyze different cases of reflections across a line.

Finding and/or designing a menu of equally weighted synthesizing projects to end a unit can be a challenge. Simplify the task with this menu of individual and group projects meant to accompany a study of The Crucible. Presentations,...

Proving triangles are similar is often an exercise in applying one of the many theorems young geometers memorize, like the AA similarity criteria. But proving that the criteria themselves are valid from basic principles is a great...

A brief summary and illustrations of light and how the lights rays are reflected and bent.