This article presents the results of an analysis of three Slovenian textbooks for high school physics, from the point of view of simplifications and idealizations in the field of mechanics. In modeling of physical systems, making simplifications and idealizations is important, since one ignores minor effects and focuses on the most important characteristics of the systems and processes. In high school physics, simplified and idealized models play a fundamental role in learning physics concepts and laws, so it is of crucial importance that textbooks present them carefully. The review shows that in two textbooks more than a half of analyzed simplifications are not properly presented.