In this article, the authors present an inquiry-based approach to facilitate student understanding of the differences among common cloud descriptive characteristics through the use of a semi-dichotomous key developed by a former West Virginia state climatologist. The authors also demonstrate how students can analyze common class data sets that describe the outcomes from the semi-dichotomous key throughout a school day to predict future weather events. Whereas other approaches to teaching about common cloud descriptive characteristics have relied on the identification of various cloud types through the use of pictures, this approach is novel in that the authors present a semi-dichotomous key with tangible descriptions to help students differentiate among subtle variations in physical characteristics. Furthermore, student analysis of common class data sets that describe the sequential change in cloud types over relatively short periods of time are then used to develop hypotheses about the changes in atmospheric conditions that may follow such observations. (Contains 5 figures.)