Instructors often provide feedback to their class in multiple ways. One way is through their follow-up behaviors, which are the specific strategies instructors implement after active learning activities. These behaviors could play an important role in student learning as students receive feedback from the instructor. However, there is little research on the effects of different types of follow-up behaviors. Follow-up after active learning can be seen as a form of discourse between the instructor and the entire class. Previous researchers developed the Classroom Discourse Observation Protocol (CDOP) to analyze discourse between the instructor and individual students or small groups. We used CDOP as a starting point to develop and validate a new protocol, the Follow-Up Discourse Observation Protocol (FUDOP), to characterize instructional follow-up behaviors to the entire class after active-learning activities. We then used FUDOP to characterize follow-up behaviors of multiple instructors in introductory biology courses at three different universities. We measured consistent differences in these behaviors across instructors but not within instructors, demonstrating that instructors may engage in consistent follow-up behaviors. FUDOP could allow instructors and researchers to better measure and analyze follow-up behaviors and their effects, which could in turn provide guidance to instructors and faculty developers.