Despite many studies conducted on TPACK, the relationships between the components of the framework and how to perform TPACK assessment remain to be important research questions. The aim of this study is to shed light on these two questions by analyzing lesson plans collected from 138 preservice mathematics teachers obtained from a technology-integration course over a period of five years. An instrument that describes each component of the TPACK framework was developed and applied to performance-assessment of preservice teachers. The analysis is augmented by a self-assessment survey to compare and contrast the differences between the two. According to the results, four knowledge domains within the TPACK framework could be distinguished, which are denoted as Core, Tech, TPACK-P, and TPACK-C. The performance- and self assessment based measures were found to yield similar results except for pedagogy related knowledge domains, in particular for pedagogical knowledge (PK), technological pedagogical knowledge (TPK), and the TPACK.