Student-to-student peer review or peer feedback is commonly used in student-centered or active-learning classrooms. In this article, we describe a footnoting exercise that we implemented in two of our undergraduate courses as one way to encourage students to acknowledge collaborations and contributions made during peer-review processes. This exercise was developed in response to a teaching problem well documented in the literature and often experienced firsthand in our own courses: students do not always transfer to future iterations of their work what they have learned in response to previous feedback. Following a description of the footnoting exercise, we analyze the resulting footnotes that the students produced. Finally, we discuss possible improvements to the assignment and avenues for future research. Contains a bibliography.