Do you know this? Some children cannot solve even simple mathematical tasks. What is the reason for this? In school, mathematics is often taught in a very abstract way. Children with a learning disability or dyscalculia lack the everyday context to understand numbers and quantities. However, even while playing, children engage in activities where mathematical skills play a role. Quantities are counted, perceived, and compared. Only by comparing quantities do they recognize their significance. Who has more candies, who has the most candies? The Number Driver offers a new approach within occupational therapy treatment. The practice-oriented concept for understanding quantities through activities in the number range up to 20 is based on the ICF-CY, MOHO, CMOP-E, and neurophysiological foundations for learning. It includes ten sequential thematic steps.