Decomposition: A K-8 Computational Thinking Learning Trajectory.

As new initiatives in computational thinking and computer science (CS/CT) are being developed and deployed, it is important to identify and understand the key concepts that are essential for student learning. In this study, we present the phases of construction of a learning trajectory (LT) for Decomposition in the context of CS/CT in K-8 education. From an extensive literature review, 63 learning goals representative of decomposition understanding and practices were identified and synthesized into 13 consensus goals. The focus of this paper is how relationships between these consensus goals were identified and used to place the goals into a learning trajectory. We discuss the theories and frameworks that guided the trajectory's construction as well as the methodology and justifications used to draw pathways through the trajectory in each phase. Finally, we discuss potential uses for the trajectory and suggest further explorations for decomposition in CS/CT.