# Montessori Constructive triangles Box 3 Presentation

MATERIALS:

Box 3 is a hexagonal box which contains the following 11 triangles:

·  3 yellow obtuse angle isosceles triangles with black lines opposite the obtuse angle on the longer side.

·  3 yellow obtuse angle isosceles triangles with the black line on both sides containing the obtuse angle.

·  2 grey obtuse angle isosceles triangles with the black line on one of the sides containing the obtuse angle.

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

·  1 large yellow equilateral triangle with the black lines on all the sides.

OBJECTIVES:

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.

CONTROL OF ERROR:

The black lines.

Visual

AGE:

4 – 4 ½ years approx.

PRESENTATION:

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

1.    Take the large yellow equilateral triangle and ask the child to make a shape using the 3 isosceles triangles. He should easily make the hexagon shape, having practised with the other boxes.

2.    Take 3 more yellow isosceles triangles and make a shape with them using the black lines as guidelines. Make an equilateral triangle. This equilateral triangle is the same as the one that forms the centre of the hexagon. Prove it by building these three triangles on top of it. Now the child will know that he can use the 6 yellow isosceles triangles to form a hexagon.

3.    The two red obtuse angle isosceles triangles form a rhombus.

4.    The two grey obtuse angle isosceles triangles form a parallelogram.

5.    Show the child that the hexagon built with the 6 yellow isosceles triangles can be split into 3 rhombi.

PRESENTATION 2:

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