In this study, we investigate the knowledge of teaching assistants (TA) and student assistants (SA) using a qualitative data analysis method. We selected 20 cases, and the results were classified into four categories, i.e., identifying and analyzing problems, ingenuity in teaching, cooperating and sharing information, and reflection. Based on our results, we developed a guidebook and rubric based on the self-assessment criteria and further used these in the same class in the subsequent year. We observed that the guidebook and rubric helped to quantify the completeness of their teaching activities. 90% of the students answered that the teachings of TA and SA can be easily understood, and more than 80% of the students answered that they required TAs and SAs