In this commentary, I examine some of the distinctive, foundational difficulties in learning fractions and other types of rational numbers encountered by students with a mathematical learning disability and how these differ from the struggles experienced by students classified as low achieving in math. I discuss evidence indicating that students…

Implementation of evidence-based practices (EBPs) is paramount to students' development of mathematics proficiency. This study investigated "practice-based evidence" of interventionists' actual use of explicit mathematics instruction, a well-established EBP. Specifically, this study analyzed direct observation data collected in a…

This study investigated if developmental dyscalculia (DD) in children with different profiles of mathematical deficits has the same or different cognitive origins. The defective approximate number system hypothesis and the access deficit hypothesis were tested using two different groups of children with DD (11-13 years old): a group with…

Numbers may be manipulated and represented mentally over a compressible number line oriented from left to right. According to numerous studies, one of the primary reasons for dyscalculia is related to improper understanding of the mental number line. Children with dyscalculia usually show difficulty when they have to place Arabic numbers on a…

The current study examined the development of two effects that have been found in single-digit multiplication errors: relatedness and distance. Typically achieving (TA) second, fourth, and sixth graders and adults, and sixth and eighth graders with a mathematics learning disability (MLD) performed a verification task. Relatedness was defined by a…

Case studies describe the positive responses of two elementary learning disabled students involved in an experimental number fact program. The program emphasized development of strategies matched to individual learning needs in a nontraditional approach to the organization of addition facts. (Author/CL)

This study examined problem solving and number-fact skills in two subgroups of third graders, those (n=12) with difficulties only in mathematics (MD-specific) and those (n=12) with difficulties in both reading and mathematics (MD-general). On both story and number-fact problems, the MD-general group performed worse than nonimpaired students,…

This study compared instruction in addition using either a minimum addend strategy or drill and practice with 84 students either with or without learning disabilities (LD). Students with LD improved significantly only in the strategy condition, whereas general education students improved in both the strategy and the drill-and-practice conditions.…

Two 9-year-old boys are described who performed in the normal range on measures of IQ, language ability, and reading. The boys were unable, however, to acquire elementary numerical skills and also manifested other specific cognitive deficits associated with the Gerstmann syndrome. (Author)

In this study, six elementary grade children with developmental dyscalculia were trained individually and in small group settings with a one-semester program stressing basic numerical knowledge and conceptual knowledge. All the children showed considerable and partly significant performance increases on all calculation components. Results suggest…