This practical volume from our handbook series for kindergarten, preschool, and elementary school is a great help for all educators and teachers who want to introduce children to the fundamentals of mathematics holistically using the Montessori principles of head, heart, and hand. All mathematics materials are initially presented in color photographs. Following that, the authors explain step by step important exercises developed and recommended by Maria Montessori. This makes them very easy to understand even without specific Montessori prior knowledge. It includes many playful ideas for discovering number spaces up to 10, 20, 100, and 1000, as well as for introducing the thinking process in the four basic arithmetic operations in a child-friendly way. The volume contains: exercises on quantity and number with numerical rods, sandpaper numbers, spindle boxes, as well as loose digits and counting chips; exercises for linear counting with bead bars, unit beads, square chains, hundred boards, and hundred carpets; exercises for systematic counting with bead bars, strip and bead boards for addition, subtraction, multiplication, and division; exercises on the decimal system with golden bead material.