Geometry and Spatial Relations: Mirror, Mirror


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In this math lesson, learners use hinged mirrors to discover that regular polygons are composed of triangles tessellating around a center point. Learners then sketch these triangles on paper models of regular polygons with 3 to 10 sides and compute the measure of the center angles formed by these triangles in each of the different polygons. Next, learners explore geometric concepts as they use mirrors and paper polygons to determine which regular polygons tessellate. Learners are challenged to give reasons why some polygons tessellate and others do not.

Quick Guide


Preparation Time:
30 to 45 minutes

Learning Time:
1 to 2 hours

Estimated Materials Cost:
1 cent - $1 per group of students

Age Range:
Ages 8 - 11

Resource Types:
Activity, Lesson/Lesson Plan

Language:
English

Subjects


  • Mathematics
    • Geometry
    • Measurement
      • Circles
      • Polygons
    • Reasoning and Proof
  • The Nature of Technology
    • The Design Process
      • Problem Solving

Audience


To use this activity, learners need to:

  • see
  • read
  • touch

Learning styles supported:

  • Involves hands-on or lab activities

Other


This resource is part of:

Access Rights:

  • Free access

By:

Rights:

  • All rights reserved, PBS, 2012

Funding Source:

  • US Department of Education