Tri, Tri Again

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Learners estimate how many small triangles will fill a larger shape. Then they use a triangle stamp (or stencil made from a file folder) to fill the larger shape with triangles. This activity is good for young learners to investigate estimation, and to see that larger shapes can be broken down into smaller shapes. When learners set up a free account at Kinetic City, they can answer bonus questions at the end of the activity as a quick assessment. As a larger assessment, learners can complete the Bug Blaster game after they've completed several activities.

Quick Guide

Preparation Time:
5 to 10 minutes

Learning Time:
10 to 30 minutes

Estimated Materials Cost:
$1 - $5 per student

Age Range:
Ages 8 - 11

Resource Type:


Materials List (per student)

  • Outlines of large shapes (3 or 4 copies of each)
  • Triangle rubber stamp and ink pad
  • (optional) Triangle stencil (made from file folder) and marker


  • Mathematics
    • Geometry
      • Plane Geometry
    • Measurement

Informal Categories

  • Arts and Crafts


To use this activity, learners need to:

  • see
  • read
  • use mouse
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


Components that are part of this resource:

Includes assesments for student learning:

This resource is part of:

Access Rights:

  • Free access


  • American Association for the Advancement of Science


  • All rights reserved, American Association for the Advancement of Science, 2009

Funding Source:

  • National Science Foundation