Using Max Weber's theory of ideal types, the authors classify the formative assessment techniques used by 12 college instructors. Their data reveal two pairs of opposing preferences: (1) highly preplanned vs. highly emergent and (2) focused on individual students vs. focused on the class as a whole. Using interview data, they illustrate how each type of instructor adopts practices consistent with research-based pedagogy, even while he or she may be unaware of the research base. The resulting composite case studies may serve as a reflection tool for instructors and professional developers pursuing proven formative assessment strategies.