Maria Montessori emphasized the importance of mathematics for the personal development of every child. The mathematics materials recommended by Montessori, such as the colored bead stairs, the Seguin boards I and II, and the short bead chains, invite exploration and experimentation. By engaging all the senses, children playfully gain mathematical insights. The accompanying templates in this volume deepen knowledge and elevate it to a cognitive level. The child's thinking and organizational structures are supported and expanded. All important aspects of the concept of numbers are taken into account. The materials are versatile: they are suitable for both deepening understanding and as differentiation tools in teaching. The templates can be freely compiled into workbooks. The materials are tried and tested in practice.