Abstract: The starting points of this paper are some principles of the theory of RME - Realistic Mathematics Education, one of the most important research branches in the field of Mathematics Education. To apply the theoretical knowledge presented, the selected example is Pythagorean theorem, one of the most classical and fundamental knowledge, holding a particularly important position in the history of mathematics. The application of Pythagorean theorem in certain realistic mathematical problems will be presented in order to partially improve the teaching of mathematics in secondary school.
Keywords: Realistic Mathematics Education, Realistic Mathematical Problems, Lower Secondary Mathematics Teaching, Pythagorean Theorem.