The study focusus initially on a state-of-the-art about the empirical and theoretical grounding of the development of the concept of time, time intervals and time relationships. On the base of an analysis of the literature, an overview will be developed of didactical strategies to influence the development of the concept of time, time intervals and time relationships in learners of 5-12 years in primary school. In a second phasea cross-sectional study is set up to study a variety of time representations among primary school children and teachers. In a third phase, an intervention study is set up with tools that help to represent time, time intervals and time relationshipsin a variety of alternative ways.