ABSTRACT
This chapter investigates preschool-aged student's explanations of number while subitizing, and characterized nuances in their subitizing development, and highlighted gradations both within and between perceptual subitizing and conceptual subitizing. Drawing on the work of Sarama and Clements, the chapter reveals that subitizing shifts from reliance upon perceptual processes to reliance upon conceptual processes, described as conceptual subitizing or groupitizing. The chapter compares student responses from the conceptual analysis to conduct a retrospective cross-student analysis. It examines an initial stable second-order thinking model for each of the four students; and evaluates a cross-student analysis comparing each child in terms of how they cognitively reorganized their number schemes when engaging in subitizing activity. The chapter highlights the developmental patterns do provide a theoretical base for future research to further verify and document the development of early childhood mathematics related to subitizing.
