Abstract: A mathematical teaching/learning aid includes a set of thin mathematical cards or blocks, the set including six different types of blocks that represent the numbers +1, -1, +X, -X, +X.sup.2, and -X.sup.2, respectively. A plurality of blocks of each type are included in the set. The numbers +1, -1, +X, -X, +X.sup.2 and -X.sup.2 are referred to as "block type" indicia, and are printed in the center of the two opposed major faces of each corresponding type block. Four edge indicia or dimensions are printed adjacent to each of the respective edges of each face of each block. The product of the edge indicia at adjacent edges of each face is equal to the "block type" indicia of that block. Mating edge alignment tabs and notches or mating edge alignment indicia are provided at or adjacent to each edge of each block to allow edge-to-edge mating of each block with another block in only one configuration.