“…Therefore it is a cognitive shift that happens when previously held understanding, inner layer understanding, acts are informed by outer layer knowing that ultimately leads to further outer layer understanding (Pirie & Martin, 2000). There are few studies that show that folding back extends learners' existing understanding of mathematics concepts (Delgado, Codes, Monterrubio, & Astudillo, 2014;Martin & Towers, 2016;Wright, 2014). Using Tall's (2008) argument, learners' geometric development builds on experiences that they have met before.…”