The purpose of the Constructive Triangles is to allow the child to explore and experiment with form and geometry. They are "constructive" because the triangles are used to form other figures. Eventually, the child comes to the realization of how new shapes and figures can be formed using only varying triangles and come appreciate the relationship between figures. Later, in the Elementary years, combinations of Constructive Triangle boxes are utilized to demonstrate the Pythagorean Theorem.e
The children in my class have recently become more interested in using the five different boxes. Many times during our Montessori work sessions, the kids will ask for lessons with one or more of these boxes. One of the aspects of the material which I value is the option of extension work. For example, once the children are comfortable working with the various boxes, they can begin extending the lessons via different materials. This may include making discoveries and experimenting with paper, paints, and colors through the creation of their own Constructive Triangles!
My dear husband made a video of me presenting the Triangular Box during one of my nightly study sessions (in my PJ's!). I find it a useful tool to be able to replay and watch myself give the lesson because often, I see on video what I miss in real-life! The direct aim of the material is for the child to realize that lines drawn on an equilateral triangle can be divided into different types of triangles:
By the way, that is Big Stuff's hand creeping in at the end...
I am very much enjoying the presentations with the Constructive Triangles and look forward to more lessons in the classroom with these types of materials.