The conception of the school subject mathematics depends on the understanding of mathematics as a scientific field. The main conception of mathematics are: mathematics as a method of prediction by means of formal calculi and mathematics as a language of science. The structural conception of mathematics is based on its logical construction and couldt be the model of mathematics in education, where the pedagogical and psychological aspects are very important. Mathematics is necessary to prepare for specific educational goal or purpose. Mathematics is designed to contribute to the development of those abilities, understandings, attitudes, and behaviour patterns which should be the common experience of all educated people. School mathematics should stress the heritage with which the subject contributes to the development of civilization. All these aspects lead to the didactic structure of school mathematics. The didactics structure of primary school geometry is in my opinion based on these principles: dividing space, filling up space, motion in space and the dimension of space.