Constructive Triangles, Large Hexagonal Box

Material

1. Invite the child to the lesson. 
2. Take out the red triangles.  
3. Take out the gray triangles.  
4. Place the lid back on the box. 
5. Slide the red triangles together by the black lines, forming a rhombus.  
6. Slide the rhombus to the top left of the rug. 
7. Slide the gray triangles together by the black lines, forming a parallelogram.   
8. Slide the parallelogram to the right of the rhombus.  
9. Take out the equilateral triangle and three yellow obtuse-angled isosceles triangles with the black lines on one side.  
10. Place the lid back on the box. 
11. Slide them together by the black lines to form a hexagon.  
12. Slowly fold the triangles over on top of the equilateral triangle. 
13. Examine how they make the same shape. 
14. Unfold the triangles forming the hexagon once more. 
15. Take out the three remaining yellow triangles. 
16. Place the lid back on the box.  
17. Slide them together by the black sides to form an equilateral triangle. 
18. Superimpose the equilateral triangles on top of the 1 large yellow equilateral triangle in the center of the hexagon.
19. Slide two of the yellow triangles away from the 1 large yellow equilateral triangle, to form a rhombus.
20. Repeat this step two more times, to create a total of three rhombi.
21. Place the red rhombus on top of the new yellow rhombi, to show the child that they are the same.
22. Randomize the triangles and invite the child to explore.

Exercises

Child works independently.

Language

None.

Control of Error

The black lines on each triangle.

Direct Purpose

To show that joining together triangles forms other straight line figures. 

Indirect Purpose

Preparation for geometry.

Age

4 to 5

Notes

This box explores isosceles obtuse triangles and deals with the concept of equivalence.
Red emphasizes that there are three rhombi in the hexagon.
The gray shows that the parallelogram is equivalent to the rhombus.