Student have different levels and educational needs. Education must be adapted to the differences between pupils. Differentiation is the way a teacher handles the differences between pupils by varying such things as instruction mode and instruction time. With divergent differentiation closes the teacher as much as possible to the individual levels and educational needs of the children. The teacher facilitates the learning process of the students. The method of Practical Differentiation already exists. Fred Janssen of the University of Leiden (ICLON) will conduct an impact assessment and on this basis, prepares a manual, supplemented with best practices. The teachers are first trained. Then they will implement what they have learned. This is followed by the effect measurement and the processing of the results in a manual.