The purpose of this study is to determine the mental models of elementary school students on seasons and to analyze how these models change in terms of grade levels. The study was conducted with 294 students (5th, 6th, 7th and 8th graders) studying in an elementary school of Turkey's Black Sea Region. Qualitative and quantitative data collection methods were used in the study. The students first were asked 3 open ended questions (one of them was a drawing) in order to determine their mental models on seasons. Following this, the students took an achievement test on seasons that consisted of 4 multiple questions. Quantitative data were analyzed by SPSS 20.0 while the qualitative data were analyzed by the researchers by using content analysis technique. The results of the study showed that the students construct the formation of seasons in various ways in their minds. However, differently from the literature, the presence of some new mental models was found. For a full understanding of the seasons, the necessity of a set of pre-learnings has been recommended. It will be useful to design basic activities based on hands-on and learning by doing which will enable the most effective learning and to put this in the textbooks in the most suitable way. Additionally tangible physical-scale hands-on models, 3D simulation modeling and planetarium environment should be used in students' education about formation of seasons.