This article describes the experience of a group of first-grade teachers as they tackled the science process of classification, a targeted learning objective for the first grade. While the two-year process was not easy and required teachers to teach in a new, more investigation-oriented way, the benefits were great. The project helped teachers and students focus on "doing" science, developed teachers' formative assessment strategies, and showed teachers the value of allowing students different ways to share what they know or how they do things. (Contains 2 figures.)