Design Based learning (DBL) as an educational approach which is emerging in primary education. Because of the limited availability of prescribed teaching materials for DR, learning activities are often developed by instructors themselves. However, it is often difficult for teachers to develop DBL activities. The paper investigates how primary school teachers can be supported in developing successful DR learning activities, in which pupils can develop both core curriculum objectives and 21st century skills. The research questions are: How can teachers be supported in the design of DBL activities aimed at concrete learning objectives? Are teachers able to apply the DBL creation tool as intended; to follow the design strategy offered, to reflect on the DBL activities using the tool and to improve the design iteratively? Are teachers able to successfully develop DBL learning activities using the tool? The paper describes the development of a tool that supports primary school teachers in creating DBL teaching materials. A web-based tool has been realized iteratively by means of design research. The resulting supports the teachers in developing 21st century education and encourages the teacher to reflect, even if it does not yet produce complete teaching materials for the classroom. However, in order to be effective in promoting DBL, there is a need to integrate the underlying concepts of DBL (such as incorporating design generations into the course material) even more extensively into the tool and to supplement it with an explicit pedagogical strategy and concrete assessment procedures.