Mathematical teaching aid

摘要

The seven shapes for the teaching aid are cut from a basic square by linking the mid points (M1,M2) of two opposite sides with opposite corners (A,C) and by taking the orthogonal cuts from these lines to the other corners (D,B). The cuts leave a small square (IV) in the centre and two identical trapeziums (III) as well as two pairs of right angled triangles (I and II) with the dimensions of one triangle (II) twice that of the other (I).The square and the trapeziums can be made up of triangles similar to the smaller triangle. The shapes can be assembled into different combinations representing different mathematical problems. They can be cut from wood or plastics and can be assembled with simple fastenings.