“…The ability to accurately assess magnitude is thought to be key for consolidating properties of whole numbers and rational numbers, since magnitude is a unifying property of all numbers (Siegler, Thompson, & Schneider, 2011) and rational number magnitude knowledge is related to future mathematics achievement (Bailey, Hoard, Nugent, & Geary, 2012; Booth & Siegler, 2008; DeWolf, Bassock, & Holyoack, 2015; Fazio, Bailey, Thompson, & Siegler, 2014; Rittle-Johnson, Siegler, & Alibali, 2001, 2012; Siegler & Pyke, 2013). Students at risk for mathematics difficulties demonstrate pervasive and systematic misconceptions related to estimating rational number magnitude (e.g., Jordan et al, 2016; Malone & Fuchs, 2016), but much of the research has centered on common fractions
. It is unclear whether the development of decimal magnitude understanding among at-risk students, the focus of the present study, parallels that of fraction magnitude understanding.…”