This presentation examines the implementation and impact of the Mathematics Design Collaborative (MDC) in ninth grade Algebra I classes in Kentucky. Through its use of one- to two-day formative assessment lessons (FALs) developed by the Shell Centre, MDC seeks to support teachers in their transition to the Common Core math standards and practices. This presentation includes a review of how the FALs are designed to incorporate deeper math reasoning and cognitive complexity, as well as findings from the implementation study.