Many high school and undergraduate students enter science courses feeling intimidated by course content and unsure of their abilities. Teachers are frequently challenged in mixed-level and interdisciplinary courses to ascertain and honor students' levels and areas of experience. In these cases, the application of critical pedagogy techniques can create a culture of caring and thereby allay student anxiety and increase student motivation and success. Here I describe a simple instant polling exercise that employs critical pedagogy to stimulate dialogue about students' experiences with course content. This exercise is especially useful for mixed-level and interdisciplinary science courses, and can be easily adapted for small or large classes.