This set of blocks includes fifteen pieces in a variety of square and round fraction shapes. They can be used as simple building toys, or to explore basic fractional relationships as well. The blocks are made of solid rubberwood from sustainable growth forests, and are finished with water-based stains which will not chip or flake off. The cubes measure 3.5 cm (about 1.5") per side, and all the other pieces are proportionally sized (half, double, etc.).