This study aimed to reveal the experiences of 11th grade students related to specializing, generalizing, conjecturing and proving stages of mathematical thinking. Worksheets, each consisting of 9 questions included the stages of mathematical thinking, and this pilot study was applied to 24 students. The results of the study demonstrated that student achievement decreased as the stages of mathematical thinking progressed. From this point of view, students were found to demonstrate a good performance in specializing stage and to have a big difficulty in proving stage. Moreover, the students' answers in generalizing and conjecturing stages were observed to accumulate under verbal and algebraic codes and in proving stages the answers were found to accumulate under the codes of arithmetic, geometric and algebraic. Suggestions are made based on the results of the study.