Angles of a Triangle: Triangles in the Trees

This is one lesson in a larger Unit Plan that covers many properties of triangles and several other theorems.  It has proofs, real world problems, constructions, a unit project, assessments, and more.  In Lesson 9, “Triangles in the Trees (Angles of a Triangle)”, students investigate the Triangle Sum Theorem, Triangle Inequality Theorem, and Exterior Angle Theorem.  One of the activities is a hands-on activity. Includes lesson plan, and a variety of downloadable student handouts (with and without Geometer's Sketchpad instructions).  The entire unit plan can be found here. The Lesson investigates Triangle Sum Theorem with a hands-on activity. The Triangle Inequality Theorem is discovered through a drawing activity, as is Exterior Angle Theorem. There are also several real world connections.

Standards & Objectives

Learning objectives: 

Essential Questions:

  • What properties of sides and angles of triangles are used in everyday situations?
  • Why should we study Triangle Sum Theorem, Triangle Inequality Theorem and Exterior Angle Theorem for Triangles?

 

Lesson Variations

Blooms taxonomy level: 
Understanding

Helpful Hints

Materials:

  • Worksheets
  • rulers 
  • compasses
  • protractors
  • computer with internet access

References

Contributors: