Nurnberger-Haag J, Wernet JL. Sparking Surprise: A Negative Number Game to Promote Productive Concepts of Addition and Subtraction. ojsm [Internet]. 2019 Jun. 29 [cited 2026 Apr. 29];82(1). Available from: https://www.osu.tests.sfulib4.publicknowledgeproject.org/index.php/OJSM/article/view/6663