In this article, the authors are interested to measure the preservice teachers' Pedagogical Content Knowledge (PCK) and their personal constructs of teaching about mathematics lesson plans during their teacher education program. The results of the content analysis show that the constructs of the pre-service teachers have a wide variation and could be summarized within different themes. TELPS could also indicate whether there is a difference between first semester pre-service teacher students’ PCK and final semester pre-service teachers’ PCK. The authors conclude that the development of PCK is an important element of any teacher education program, and TELPS appears to be useful in determining pre-service teachers’ PCK.