“…There are many reasons that could explain the observed differences in students' understanding of equivalence across the countries. For example, classroom instruction could contribute to students' understanding of equivalence, such as feedback, perceptual support, physical experiences with the balance model, use of relational words, use of inequality symbols with the equals sign, support for students' self-explanation, support for students' use of different solution strategies; nonsymbolic instruction (see Alibali et al, 2009Alibali et al, , 2018Bajwa & Perry, 2019;Chesney et al, 2018;Chow & Wehby, 2019;Fyfe et al, 2012;Hattikudur & Alibali, 2010;Otten et al, 2020;Rittle-Johnson, 2006). Moreover, differences in understanding of equivalence across the countries could partly be explained by curricula and their implementation (e.g., Cai et al, 2011;Grouws et al, 2013), the length of an average school day ("School Years around the World," 2017), the differences between parent-related factors such as parents' education and support and expectation from their children (e.g., Ahn & Baek, 2013;Kim & Bang, 2017;Ma et al, 2013;Xu & LeFevre, 2018), and family socioeconomic status (e.g., Hu et al, 2018).…”