4 o 4.5 years approx.
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
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.