The Course-based Undergraduate Research Experience (CURE) instruction study investigates how instructors make decisions when supporting students through research challenges. The goal of this research is to characterize instructor actions as well as the rationale behind their actions. To meet this goal, we conducted think-aloud interviews where experienced instructors reasoned through different teaching scenarios that illustrated student research challenges. This study is funded by a National Science Foundation STEM Ed IPRF grant to Dr.Cooper. Findings from this work are being prepared for publication.