#590: Making Decomposition Visible in Early Elementary Computational Thinking

We investigate how decomposition emerges in early elementary computational thinking (CT) through a microgenetic analysis of two first-grade students engaged in eight mathematics–coding lessons using a coding robot toy. Rather than presupposing large, open-ended problems for decomposition, we foreground units—what students use as a unit when interpreting problems. Findings show (a) prior intuitive units (e.g., “go-and-return”) that diverge from those of the robot’s syntax, (b) shifts toward robot-aligned units (move one grid unit; rotate 90° in place), and (c) formation of composite units by grouping recurring sequences of atomic units via a function tile. We conceptualize early CT decomposition as changes in the unit in students’ problem solving, offering a developmentally appropriate lens grounded in observable activity.