Conceptual learning is a uniquely human behavior that engages all aspects of individuals: cognitive, metacognitive, and affective. The affective domain is key in learning. In this paper, that authors have explored three affective constructs that may be important for understanding biology student learning: self-efficacy--the set of beliefs that one is capable of performing a task; sense of belonging--when one feels a part of a particular group; and science identity--the extent to which a person is recognized or recognizes himself or herself as a "science person." The ideas expressed in this article are intended to help all biology instructors consider the role of affect in biology teaching and learning and to provide starting points for instructors who may wish to collect informal classroom evidence that may give them insights into their students' self-efficacy, sense of belonging, and science identity.