Color CubesThis classic toy from Froebel USA features colorful 30mm solid wood cubes, where each block has 4 sides of solid colors (red, white, blue and yellow) and 2 sides divided diagonally between red white and yellow blue. All 25 blocks are identical, allowing millions of creative design possibilities. Introduced in the 1920's and often used by psychologists to test critical thinking skills (Kohs Block Design Test, Weschler WISC V visual spatial test), this