The Constructive Triangles
Rectangle Box 1
When children are introduced to the triangle, they are told that we call the triangle constructor because it is the smallest possible geometric plane figure (there cannot be other closed figures with fewer than three sides) and it is the constructor of all other figures. In one way or another, all straight-sided figures are a multiplication of the triangle.
The Rectangle Box I is used to demonstrate that all plane geometric figures can be constructed from triangles. There are five boxes of constructive triangles in all but this is the first box we present. In this box, there are three pairs of large right-angled scalene triangles in three different colors; a pair of red triangles that form an isosceles trapezoid bisected diagonally, a pair of equilateral yellow triangles and two different colored pairs of large right-angled triangles. Black lines are painted on one side of each triangle to mark where they are joined with another triangle in the box that is congruent. When joined, they form a rectangle, four parallelograms, a trapezoid and a square. This not only is preparation for measurement but for later concepts in equivalency, similarity, and congruency. -Dr. Pamela Autrey
The Rectangle Box I is used to demonstrate that all plane geometric figures can be constructed from triangles. There are five boxes of constructive triangles in all but this is the first box we present. In this box, there are three pairs of large right-angled scalene triangles in three different colors; a pair of red triangles that form an isosceles trapezoid bisected diagonally, a pair of equilateral yellow triangles and two different colored pairs of large right-angled triangles. Black lines are painted on one side of each triangle to mark where they are joined with another triangle in the box that is congruent. When joined, they form a rectangle, four parallelograms, a trapezoid and a square. This not only is preparation for measurement but for later concepts in equivalency, similarity, and congruency. -Dr. Pamela Autrey