Nurnberger-Haag J, Wernet JL. Sparking Surprise: A Negative Number Game to Promote Productive Concepts of Addition and Subtraction. ojsm [nternet]. 2019 Jun. 29 [cited 2026 Nov. 7];82(1). vailable from: http://voyager.janeway.systems:9999/index.php/OJSM/article/view/6663