Mar 312016

Montessori Lesson

Montessori Constructive triangles Box 4 Presentation


Box 4 is a hexagonal box which contains the following 18 triangles:

· 1 yellow equilateral triangle with no black lines.

· 3 green equilateral triangles, two with the black lines on one side and one with black lines on two sides.

· 2 red equilateral triangles with the black line on one side.

· 6 red obtuse angle isosceles triangles with the black line opposite the obtuse angle,

· 6 grey equilateral triangles with the black lines on two sides.


To give the child the opportunity to experiment with various geometric shapes.

To discover, at a sensorial level, the various ways these shapes can be divided and combined to form other shapes.

For later work in Maths and Geometry.


The black lines.



4 – 4 ½ years approx.


Individual exercise done at a table or on a floor mat.

1.    Take the 6 small grey equilateral triangles, construct a hexagon, keeping the non-line sides outwards. Invite the child to do the same after dismantling it for him. Put the hexagon to one side.

2.     Take the 1 yellow equilateral triangle and the three red obtuse angle triangles and make a hexagon.

3.    With the other 3 red obtuse angle triangles, allow the child to make an equilateral triangle on top of the yellow equilateral triangles, which was used to build the hexagon.

4.    Take away the yellow equilateral triangles and construct the hexagon using the 6 obtuse angle isosceles triangles.

5.     The two small equilateral triangles form a rhombus.



6.    The three small green equilateral triangles form a trapezium

7.    Look again at the grey hexagon, it divides into 2 trapeziums. Proceed to build the green trapezium on top of the grey trapezium. The grey hexagon also divides into 3 rhombi.

8.    The red hexagon will also divide into three rhombi.


Give a three period lesson on the names of the various triangles.

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