Investigate relationships between angles, arcs, and segments in circles. Pupils use geometry software to discover the relationships between angles, arcs, and segments associated with circles. Class members use similar triangles to...

Polygons — it's all about the angles. Groups work with dynamic geometry software to find the sum of the measures of the angles of various polygons. After finding the information for several polygons, the groups generate a formula that...

Provide your emerging mathematicians with the tools to learn as they incorporate auxiliary lines to solve unknown angle proofs in this continuing segment. They decipher information from a diagram to uncover the missing pieces and...

Lead the class in a Greek history lesson with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete...

Try to find the triangles in various polygons. An investigation has learners develop a formula for the sum of the measures of the interior angles of a polygon. They use manipulatives to partition each polygon into triangles, then...

Junior geometers discover that polygons can be decomposed into triangles and that the number of triangles can be determined by a rule. Note that the Geometer’s Sketchpad® software is required to carry out all components of this...

Your geometry learners use their knowledge of various geometric concepts to write proofs. Starting with givens containing parallel line segments with transversals and triangles and quadrilaterals, and the mid-point and distance formulas;...

Who has the best street smarts? An educational lesson has future mathematicians analyze street maps and measure angles on the map to determine if streets are parallel. They also consider safety issues at different types of intersections.

Your geometry learners explore Angle-Side-Angle congruence in this collaborative task. The sum of the interior angles of all triangles being one hundred eighty degrees, is the key learners will discover as they explain their reasoning...

This task asks learners to prove that the segment joining the midpoints of two sides of a parallelogram is both congruent and parallel to an adjacent side of the parallelogram. The activity would be good to use in a discussion about how...

Fifth graders use pattern blocks and triagular grid paper to reivew shape names, be introduced to the concept of a tiling of the plane, and determine which pattern blocks tile the plane. They are asked if they comprehend what a...