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Exploring Triangles

Building Blocks Math, Weeks 5 & 7: Exploring Shapes and the Number 3

Young children’s understanding of triangles can sometimes be rigid and fixed.  They are accustomed to seeing equilateral triangles in a point-up orientation.

Equilateral triangle

If the shape is inverted or is no longer equilateral children may think that it is not a triangle.  

Inverted equilateral triangle
Right angle triangle

Our role is to teach the children the essential features of a triangle, expose them to diverse images of triangles, and provide opportunities for them to build and create a variety of triangles.  

Triangles are closed 2-dimensional shapes with 3 sides and 3 angles.

Here is one possible activity.  Use straws, coffee stirrers, pencils, and more.  Any straight materials in varying lengths will do! 

Two felt mats, triangle cutouts and two trays with a variety of length of sticks

Provide a defined workspace with:

  • A numeral “3” (with dot set) card
  • A variety of lengths of sticks
  •  A books to draw and record their triangles 
Felt mat, tray with a variety of lengths of sticks, the numeral 3

Designing prompts in the shape of differing triangles serves to reinforce the lesson. As children create and explore, use “math talk” to introduce and reinforce key vocabulary and concepts: sidesanglepoint, and closed shape.   There may also be some problem-solving to discuss, as two very short sides with one very long side may not make a closed shape.  

If you have plenty of materials or use paper strip sticks, children can glue down their triangles and make a triangle collage!

Triangle made with wood pieces
large wood piece triangle with small wood piece triangle inside

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