The primary purpose of this study is to determine the geometric habits of mind of classroom teacher candidates and the level of these habits. The study was conducted with 55 elementary education program students studying at an education faculty in the 2017-2018 spring term. The criterion used in the determination of the study group is that the teacher candidates should have knowledge about almost all the courses in the classroom education program and have taken courses I and II in mathematics teaching. Three worksheets were distributed to the teacher candidates as a data collection tool. Since the research is like a case study, the mathematical ideas developed by the teacher candidates about quadrilaterals and their written answers were summarized and interpreted according to the predetermined themes. When the findings obtained as a result of the research are examined in general, it can be said that teacher candidates are not sufficient in finding relationships between quadrilaterals, generalizing the relationships they find by using strategies, associating the feature valid for a quadrilateral with quadrilaterals that may have that feature, namely the whole, and making judgments.