Constructive Triangles: Second Box: Trapezoid

Age
6-9.

Materials
Box 2 -


 * Two blue equilateral triangles
 * Two blue right-angled isosceles triangles
 * Two blue right-angled scalene triangles
 * One blue obtuse-angled scalene triangle
 * One blue right-angled scalene triangle (corresponds to the red triangle from Box 1)

Presentation

 * 1) With the two small red triangles, invite the child to unite the triangles along the black lines and identify the figure obtained - a trapezoid.
 * 2) Using the two corresponding blue triangles, invite the child to form the figure which he already knows and to identify it - a trapezoid.
 * 3) Continue making other quadrilaterals using only the obverse sides.
 * 4) The directress identifies the figure obtained.
 * 5) Since it has four sides we can call it a quadrilateral.
 * 6) It is a concave quadrilateral - a boomerang (it may also be called a re-entrant).
 * 7) Invite the child to turn over one triangle to form any other figures, quadrilaterals or triangles.
 * 8) The quadrilateral is called a common quadrilateral.
 * 9) The triangle is an obtuse-angled isosceles triangle.
 * 10) Note: This triangle has great importance in the later study of the area of a trapezoid.
 * 11) Recall the figures formed by these triangles; there are four.

Purpose

 * Exploration of the triangle as the constructor of triangles and quadrilaterals.

Links
Constructive Triangles Boxes # 1-5