Different models for the electronic structure of carbon monoxide are suggested in influential textbooks. Therefore, this electronic structure offers an interesting subject in teaching because it can be used as an example to relate seemingly conflicting concepts. Understanding the connections between ostensibly different methods and between different concepts, related or conflicting, is important in academic studies. The related reactivities of CO, O[subscript 2], and N[subscript 2] and the notations of molecular orbitals are topics of interest and are discussed in detail. (Contains 3 figures.)