The document describes the development of a learning and assessment framework to evaluate students' multiplicative thinking skills in Years 4 to 8. Researchers designed rich assessment tasks and administered them to nearly 3,500 students. The tasks were based on an initial hypothetical learning trajectory identified from the literature. Student response data were used to refine the tasks, scoring rubrics, and a final learning and assessment framework consisting of nine levels of increasing complexity in multiplicative thinking. Sample assessment tasks, such as a multi-part "Butterfly House" problem, and corresponding scoring rubrics are provided as illustrations.