Instructional reforms have been called for on a national level. Little data exists as to how changes take place. This study explored the implementation of active learning practices by non-tenure and tenure track faculty over the course of a semester. Faculty were introduced to evidence based pedagogy through workshops and faculty learning communities. Their instructional practices within a semester were tracked through observations conducted using the Classroom Observation Protocol for Undergraduate STEM (COPUS). Interviews were conducted to gain insight into reasons for instructional trends. A general trend downward was observed through the semester but was not found to be statistically significant at different time-points. A possible Simpson’s paradox was detected in the collapsed COPUS categories of Instructor Guiding (G) and Students Working (SW) that may also be interfering with broad interpretation. Recommendations are made for further data collection to increase power and to use care before interpreting collapsed COPUS categories.