Workbook 4 with CD-ROM. The Thinking and Calculating workbooks provide additional practice opportunities for deepening knowledge and, of course, for homework. The task formats and topics closely align with the student books and can be independently worked on by the children. A simple reference system in the table of contents helps to quickly identify suitable tasks and differentiation offers. Review sequences also regularly appear in the workbooks. As an alternative to the workbooks, support or challenge books can also be used. Particularly in the early grades, there are often significant differences in performance among the children. These differentiated workbooks offer the opportunity to support children with deficits at their level or to challenge high-performing children with more difficult exercises.