During a two-week summer professional development workshop, teams of intermediate-level school teachers and college methods instructors crafted mathematics learning modules--activities, lesson plans, work sheets, and technology-oriented tasks--with the primary goal of strengthening students' understanding of various geometric concepts. They recast the paint bucket features of photo editing software as a teaching tool to foster discussion, debate, and heightened understanding of polygons with fifth-grade geometry students. As students "filled" geometric shapes with the paint bucket, they explored nuances of polygons too often overlooked by contemporary elementary-level textbooks. This article discusses how the paint bucket metaphor could allow one's students to build sophisticated notions of polygons in ways that are developmentally appropriate for early-grades learners. (Contains 9 figures.)