“…As the number line is central to the LMR curriculum, we are able to build on and contribute to literatures in the learning sciences on children's developing understandings of the number line [Booth & Siegler, 2008;Earnest, 2012;Petitto, 1990;Saxe, Earnest, Sitabkhan, Haldar, Lewis, & Zheng, 2010;Siegler & Opfer, 2003] as well as linear representations [Barrett, Sarama, Clements, Cullen, McCool, Witkowski-Rumsey, & Klanderman, 2012;Lehrer, 2003;Núñez, 2011;Piaget & Inhelder, 1956;Piaget, Inhelder, & Szeminska, 1960;Saxe, Shaughnessy, Gearhart, & Haldar, 2013b]. As a whole, these literatures reveal that young children show capabilities to order numbers along a linear dimension; however, only later do children show capabilities to generate uniform metric properties in their ordering of numbers.…”