At the University of Maine, middle and high school science, technology, engineering, and mathematics (STEM) teachers observed 51 STEM courses across 13 different departments and collected information on the active-engagement nature of instruction. The results of these observations show that faculty members teaching STEM courses cannot simply be classified into two groups, traditional lecturers or instructors who teach in a highly interactive manner, but instead exhibit a continuum of instructional behaviors between these two classifications. In addition, the observation data reveal that student behavior differs greatly in classes with varied levels of lecture. Although faculty members who teach large-enrollment courses are more likely to lecture, we also identified instructors of several large courses using interactive teaching methods. Observed faculty members were also asked to complete a survey about how often they use specific teaching practices, and we find that faculty members are generally self-aware of their own practices. Taken together, these findings provide comprehensive information about the range of STEM teaching practices at a campus-wide level and how such information can be used to design targeted professional development for faculty.