A guide for teachers of geometry to the new Common Core State Standards. My goal is to explain in detail how the course will transform when the CCSS come into force.
I develop that fragment of a year's course which will undergo the greatest change. I state definitions of rigid transformation, flip, turn, slide, scale, congruent and similar. I give the Rigid Motion and Scale Transformation Postulates. I then prove the core theorems, among which are the Triangle Congruence and Triangle Similarity Principles.