The problem of modernization of natural knowledge, including physics, is actively discussed in scientific and pedagogical groups. Recently, there is a tendency to simplify the school course of physics, especially in non-core classes. Nevertheless, the course of physics not only should reflect in a popular form the individual achievements of modern science, but should also be based on the methodological principles of this science: symmetry, conservation, causality, conformity, the principle of observation and simplicity to specify the types of symmetry, the principle of unity to adjust existing theories, and so on. It is necessary not to facilitate the course of physics in educational institutions, but to radically restructure it in the manner, when classical physics would act in dialectical unity with the modern one. The laws of classical physics must be understood from the standpoint of modern science: on the basis of the dialectic of necessary and accidental, the dialectic of symmetry and asymmetry, the dialectic of the process of cognition. This is necessary in order to prevent fragmentary thinking and to form in students a scientific picture of the world and a scientific worldview.