The new world of numbers optimally implements the requirements of the general educational standards and the Lower Saxony core curriculum. The relationship-rich learning offer establishes a solid connection between the content-related competency areas (numbers and operations, space and shape, patterns and structures, sizes and measuring, data and chance) and the process-related competencies (communicating and arguing, modeling, representing, problem-solving). The rich array of tasks, tailored to the respective learning phase, includes suggestions for joint teaching phases as well as opportunities for differentiation. The tasks in the student book and accompanying materials are categorized and marked according to the three areas of requirements defined in the educational standards. Tasks marked as 'crown tasks' contain differentiated questions at varying levels. The children explore problem-oriented situations, attempt to find solutions independently, take their own paths, and discover anomalies and patterns. A comprehensive range of supplementary materials provides further suggestions for the individual design of lessons. The newly developed collections of materials for 'supporting' and 'challenging' assist in the support and development of each individual child. The material collections for practical arithmetic and geometry deepen and expand the offerings of the student book. The use of whiteboards is addressed with a newly developed offering of interactive board images. New: For inclusive teaching with the world of numbers, special booklets have been developed - particularly for children who are taught with different goals in a primary school class.