Although teachers are eager to facilitate community of inquiry (CoI) in their classrooms, they also fear being unable to convey the necessary knowledge to their students in an inquiry due to the inherent involvement of conflicting views, confusion, and a lack of strict definitions about the concepts. The author argues that the banking model of education relies on certain conceptual assumptions about the nature of concepts. For the banking model to function effectively, it must initially assume that all concepts can be defined by their necessary and jointly sufficient conditions. The author goes on to argue that treating concepts as prototypes is helpful in demonstrating the necessity of collective inquiry, even for technical and scientific concepts that are strictly defined. This approach to concepts is illustrated through an inquiry design in a science class on the concept of "mixture."