Constructive Triangles: Third Box

Age
6-9.

Materials
Box 3 -


 * Twelve blue right-angled scalene triangles with no black lines. The angles measure 30, 60, and 90 degrees.

Presentation

 * 1) Isolate one triangle.
 * 2) Ask the child to identify each of the angles, and the biggest and smallest angles.
 * 3) This angle which is neither smallest nor biggest we can call the medium angle.
 * 4) The child names each angle: smallest angle, medium angle, biggest angle.
 * 5) First star: Let's unite all the triangles by their smallest angle.
 * 6) The directress positions a few and allows the child to continue.
 * 7) How many points does this star have? Twelve.
 * 8) With all of the triangles at our disposal, we can make only one star with twelve points.
 * 9) Second star: Let's unite all the triangles by the medium angles.
 * 10) How many points does this star have? Six.
 * 11) Try to make another star with the triangles that are left.
 * 12) With all the triangles at our disposal, we can make two stars with six points.
 * 13) Third star: Let's unite all of the triangles by the largest angle.
 * 14) How many points does this star have? Four.
 * 15) This symbol is very famous; it is the star of Saint Brigid, the patron saint of Ireland.
 * 16) Try to make another star like this.
 * 17) With all the triangles at our disposal, we can make three stars with four points.

Purpose
Use of the triangle as a constructor to indirectly demonstrate the following:


 * 30o x 12 triangles = 360o
 * 60o x 6 triangles = 360o
 * 90o x 4 triangles = 360o
 * 360o / 30o = 12 triangles
 * 360o / 60o = 6 triangles
 * 360o / 90o = 4 triangles
 * 360o / 12 triangles = 30o
 * 360o / 6 triangles = 60o
 * 360o / 4 triangles = 90o

Handouts/Attachments
Constructive Triangles Boxes # 1-5