The purpose of this study is to help understand what the role of a teacher is, based on practices and experiences obtained from the subject of Practices and the Teaching of Math and Supervised Training Process (PEMES). The focus of this study is on the knowledge and practices adopted in schools based on the paradigm of complexity, which may acquire meanings in a complex and unpredictable practice. The study was carried out with two students taking Math Licentiate at FE/Unicamp, through the development of the PEMES I and II subjects in the year 1999. The mentioned students were interviewed and observed ethographically in activities at the university as well as in schools. Based on these procedures we were able to make up narrations of the formation process of the licentiates. The analysis of the process they go through from student to become a teacher, which was experienced through the training period, was focused on one of them, and among other aspects, led us to the conclusion that this process is quite stressful taking into consideration problematic images, knowledge and models of actions adopted in teaching, which are acquired through life. Based on all this, we can come to the conclusion that the Teaching Practices as well as the Training Processes are a very important step in the process of formation, which requires a lot of shared ideas, theory and the exchange of information among the people involved with the educational field.