The purpose of this study is to introduce the Contingency unit of Knowledge Quartet, which is a framework used in assessing mathematics student teachers' subject matter knowledge and pedagogical knowledge, address its significance and demonstrate examples from its reflections on classroom setting. The study initially covers the type of knowledge that teachers should possess and Knowledge Quartet, which enables examining and assessing subject matter knowledge and pedagogical knowledge together. Next, general information was given regarding knowledge units of this model and it was explained including contingency components. Finally, the importance of Contingency was mentioned and some examples in classroom setting were discussed. It is thought that through this study, awareness of mathematics student teachers can be made ensured with regards to situations that teachers may encounter and that are almost impossible to plan in advance.