“…This work has attempted to measure, and in a few cases account for, individual differences in children's arithmetic performance (Hecht, Close, & Santisi, 2003;Swanson & Kim, 2007), conceptual understanding (Canobi, 2004Canobi, Reeve, & Pattison, 1998;Dowker, 1998) and strategy use (Imbo & Vandierendonck, 2007;Kerkman & Siegler, 1997). These studies reveal the importance of considering the variety of ways in which children develop understanding of arithmetic.…”