The purpose of this diploma thesis is to introduce the process of mathematical modeling, focusing on application of mathematical modeling in the class. At first, we were dealing with mathematical modeling in primary school and in high school after that. In the beginning, we have specified and explained four approaches to mathematical modeling and give examples for each access. Then we focused on modeling for primary school. First, we have described briefly the modeling process, and then, we specified various examples. Since these activities have been implemented in class, each part of school hour is worked out in detail. After that, we were dealing with modeling in high school. We have provided a variety of examples of modeling with linear, quadratic, exponential, logarithmic and trigonometric functions. At the end, we said something about program Graph which is mentioned in diploma thesis and used for charting