



Teacher knowledge of students’ mathematical thinking has been a growing research area in mathematics education. Mitchell and Marin (2015) reported that teachers in their study were not used to noticing students' mathematical thinking, with only (on average) 19% of the instances teachers identified were related to students' mathematical thinking compared to 42% related to pedagogy. Regarding what teachers notice, researchers have focused on teacher noticing of (a) students versus teachers (e.g., Mitchell & Marin, 2015 Stockero, 2008Stockero,, 2014van Es & Sherin, 2008), (b) pedagogy (e.g., task use, representation use, teacher moves) (e.g., Dreher & Kuntze, 2015 Kersting, 2008 Lee, 2020b McDuffie et al., 2014 Roller, 2016 Star & Strickland, 2008 Stockero, 2008 van Es, 2011 van Es et al., 2017 van Es & Sherin, 2008), (c) student thinking (e.g., Amador, 2016 Jacobs et al., 2010 Krupa et al., 2017 Lee, 2018), (d) classroom management or climate or environment (e.g., Amador, 2017 Mitchell & Marin, 2015 Star et al., 2011 Star & Strickland, 2008 Stockero, 2008 van Es, 2011 van Es & Sherin, 2008), (e) student-teacher or student-student communication (e.g., Scherer & Steinbring, 2007 Star & Strickland, 2008), (f) equitable issues (e.g., power, participation, bilingualism) (e.g., Dominguez & Adams, 2013 Fernandes, 2012 Hand, 2012 McDuffie et al., 2014 Turner et al., 2012 Wager, 2014), and (g) curricula (e.g., Amador et al., 2017).
