In this diploma thesis, it was investigated how well students in high school understand graphic representations of motion. Research was conducted on 48 students at Zagreb high school who were tested on interpretation of 15 graphic representations of motion. There were two separate questions that we wanted to evaluate: student’s understanding of the meaning of the slope of the motion graph and the student’s understanding of the meaning of the area under the graph. Based on the analysis of the results, it was concluded that students have equal difficulty in solving the problem of the area under the graph and the slope problem. The results that were collected during this thesis were compared with one of the American research projects that was conducted on 894 students, and it is concluded that both Croatian and American students have the same comprehension problems. This indicates that there will always be some physical concepts that will be harder to understand. Croatian students solved all tasks with significantly better accuracy than American students. This might be due to the smaller and more specific group of students that were tested since the research took part right after they completed the kinematics lectures. Based on this research, it is not possible to draw conclusions about the entire population of Croatian students. What was found is that students have most problems while understanding the negative slope of the direction and directions that do not pass through the origin, as well as the interpretation and description of graphic representations of motion. In physics classes, teachers should analyze the graphs way more and insist on the interpretation of the graphic representation while encouraging students to think more critically while finding their own solutions to the physics problems.