Think of this unit as the introduction to high school geometry.  Students will explore constructions and the tools of geometry.  They will  look at the definitions and properties related to lines, angles, quadrilaterals, and triangles.  This unit will not go into triangle congruence or similarity theorems as those are the specific work of Units 2 and 3. “The fundamental purpose of the Geometry course is to introduce students to formal geometric proofs and the study of plane figures.  Students begin to formally prove results about the geometry of the plane by using previously defined terms and notions.”  This begins here in Unit 1 with students knowing & developing definitions, proving geometric theorems, making constructions and exploring parallel & perpendicular lines.  In high school, “students begin to formalize their geometry experiences from elementary and middle school, using definitions that are more precise and developing careful proofs.”  Care should be taken to keep this unit and the course as whole on grade level by diving deeper into concepts previously introduced in middle school.  Additional depth in this unit specifically  is mainly explored through the supporting GPE standards.  Greater depth in the G-CO standards is explored in the next unit dealing with Congruence, specifically transformations & triangles.  The one exception is G-CO.13, which is a big idea of Unit 5: Circles.  Proofs can be extended to quadrilaterals inscribed in a circle G-C.3 as well.