This case study examines efforts by Lake Tahoe Unified School District (LTUSD) to improve math instruction districtwide, starting with a focused pilot at Sierra House Elementary School. Initially responding to stagnating test scores, LTUSD developed a strategy with its external partner California Education Partners (Ed Partners), which centered on capacity building by developing pacing guides, essential standards, and open-ended math tasks. Despite initial challenges, Sierra House piloted the use of these resources to create a collaborative system for analyzing student learning and refining instructional strategies. While the district faces barriers to districtwide scaling, the Sierra House model serves as a blueprint for building adult capacity and fostering instructional coherence. The study highlights the roles of leadership, strategic resource use, and collaborative structures in improving math instruction and scaling practices across a decentralized district.