Coping with heterogeneity and motivation of all students independent from theircapabilities, is one of the great challenges in primary school, especially for teaching andlearning mathematics. The project looks for opportunities for a “natural differentiation”.For the learners, it should contribute to a deeper mathematical understanding as well asto the development of general learning strategies that could lead to a higher motivation.The innovative aspect of the project is connected with a conceptual change in theteachers’ and the pupils’ mind which should lead to a change of classroom culture and asound attitude towards the nature of mathematics.Together with selected teachers, learning environments in terms of commentedteaching units will be developed and put into practice (field test 1). The videodocumentedlessons will be analyzed and evaluated with respect to allow differentiationas well as sharpening the concept of “natural differentiation”. Pupils’ motivation will bemeasured by a standardized test. After a revision of the learning environments, a 2ndfield test will follow, performed by a greater number of teachers (including measuringmotivation). These two field tests serve as a basis for offering documented best practiceexamples illustrated by video documents and pupils’ journals and documents aiming ata wider group of teachers, teacher educators and text book publishers. To ensure agreat impact, some of these materials will not only be offered in the specific differentnational languages but also translated into the other national languages as well as inEnglish.