The purpose of the project was to determine the effects of journal writing on the thinking skills of high school geometry students. The research supports the idea that writing can enhance a student's metacognitive ability. The results show that the journals served effectively in various capacities. Each student became actively involved in his or her own learning process. Writing forced the students to synthesize information and they became aware of what they did and did not know. They recognized their individual learning style and strengths and began to take advantage of those strengths. The journals served as a diagnostic tool for the instructor and they opened lines of communication between teacher and student and personalized the learning environment. The results of the project suggest that this type of journal keeping would be effective in all disciplines but it is especially recommended that it be implemented throughout a mathematics department. (Author)