Constructive Triangles

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The constructive triangles are a sensorial material that are beautiful, versatile, and useful. As with most Montessori materials found in the Children’s House, the constructive triangles invite continued repetition by the children and are also used in the Elementary environment. Heather Steinman, P3 Directress, welcomes us into her classroom and explains the work of constructive triangles. 

The Triangular Box, shown above, consists of:

  • One gray equilateral triangle, the shape and size of the box
  • One green equilateral triangle bisected from the midpoint of the          base to the apex
  • One yellow equilateral triangle divided into three equal pieces by          lines drawn from each angle to the center of the triangle (along          angle bisectors).
  • The constructive triangles are used to demonstrate that all plane geometric figures can be constructed from triangles. There are five boxes: 2 rectangular, 1 triangular, and 1 large and 1 small hexagonal. Each box contains triangles of different sizes, shapes, and colors. With the exception of Rectangular Box 2, black guidelines are painted in different positions on the triangles to help the child to construct other figures. This should be encouraged as an exploratory work that will provide a foundation for later concepts of equivalency, similarity, and congruency.

    The gray equilateral triangle allows for a child to check his own work: another example of self-assessment. A child uses this feedback to self-correct during this work.

    Thank you, Heather, for sharing this work with us!

    “Under the urge of nature and according to the laws of development, though not understood by the adult, the child is obliged to be serious about two fundamental things … the first is the love of activity… The second fundamental thing is independence.”  (What You Should Know About Your Child)