The purpose of this study is understanding the Personal Practical Knowledge (PPK) of teachers which has been done through qualitative method. Understanding PPK helps us to understand why teachers act in a specific way. In this regards, reflecting on their personal and professional narratives also help to improve their practice. This study was conducted along with 13 teachers in a non-profit primary school in Tehran. The results of the study indicate teachers’ rich knowledge of factors affecting success of the teaching profession. However, the data obtained from the observations show the difference between what the teacher describes as a successful teacher and effective teaching, and what happens in their practice. The dynamic and contextual nature of the teacher's knowledge and the different meanings and interpretations of similar experiences and events and absence of reflection are the factors that cause this differences.