Nurnberger-Haag, J. and Wernet, J. L. (2019) “Sparking Surprise: A Negative Number Game to Promote Productive Concepts of Addition and Subtraction”, Ohio Journal of School Mathematics, 82(1). vailable at: http://voyager.janeway.systems:9999/index.php/OJSM/article/view/6663 (ccessed: 7 November 2026).