4 to 4.5 years approx.
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.
CONTROL OF ERROR
The black lines.