Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...

A diameter is the longest chord possible, but that's not the only relationship between chords and diameters! Young geometry pupils construct perpendicular bisectors of chords to develop a conjecture about the relationships between chords...

Learners construct tangent lines. In this geometry activity, students identify the point of tangency, secant and tangent lines. They graph the lines on the Ti and make observations.

Students investigate proofs used to solve geometric problems. In this geometry activity, students read about the history behind early geometry and learn how to write proofs correctly using two columns. The define terminology valuable to...

Isn't paper pushing supposed to be boring? Learners attempt a paper-pushing puzzle to develop ideas about angles inscribed on a diameter of a circle. Learners then formalize Thales' theorem and use geometric properties to develop a proof...

Students explore the concept of vertex-edge graphs.  In this vertex-edge graphs lesson plan, students try to construct a graph with a given diameter, number of vertices, size, and planarity.  Students construct various...