This group of building blocks is composed of several repeating units. Through these repeating units, the modules can be freely expanded in the horizontal and vertical directions and can be joined to each other. It is more stable than ordinary geometric buildings, and can be easily built into buildings taller than the child's own height. It can be used in various architectural styles. When building blocks, it not only stimulates the imagination of children, but also allows them to experience the possibilities of various structural mechanics.