Geometry Institute | Teach North Texas

Geometry Institute

TEKS G.3 (D) identify and distinguish between reflectional and rotational symmetry in a plane figure.

  • Compare and contrast rotational and reflectional symmetry.
  • Describe how symmetry can be used as an organizational principle in biology and in mathematics.
Lesson PlanPowerPoint


  • Recognize that the measure of an angle is independent of the distance between any two points on the rays that form the angle and of the length of the representation of the rays.
  • Relate the measure of an angle to the fraction of a turn in a complete circle.
  • Investigate and define perpendicular bisector and angle bisector.
  • Describe the property that any point on the perpendicular bisector of a segment is equidistant from the endpoints of the segment it bisects.
  • Describe the property that any point on the bisector of an angle is equidistant from the sides of the angle it bisects.
Introduction to NSpirePerpendicular BisectorsDetermining Angle MeasuresPowerPoint (Intro to NSpire)NSpiring Play Time StudentsPowerPoint (QuickDraw 2)


(B) construct and justify statements about geometric figures And their properties

(E) Use deductive reasoning to prove a statement.

  • Describe paragraph, flow-chart, and two-column proofs.
  • Critically judge proofs.
  • Construct a proof about the diagonals of special quadrilaterals.
Examining Proofs Lesson PlanAltitude to the HypotenusePowerPoint (Examining Proofs)PowerPoint (QuickDraw 3)Rubric for Scoring Proofs

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