Magnitude understanding is critical for students to develop a deep understanding of fractions and more advanced mathematics curriculum. The research reports in this special issue underscore magnitude understanding for fractions and emphasize number lines as both an assessment and an instructional tool. In this commentary, we discuss how number…

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…

Learning fractions is difficult for children in general and especially difficult for children with mathematics difficulties (MD). Recent research on developmental and individual differences in fraction knowledge of children with MD and typically achieving (TA) children has demonstrated that U.S. children with MD start middle school behind their TA…

The primary goal of this review is to highlight current research and theories describing the neurobiological basis of math (MD), reading (RD), and comorbid math and reading disability (MD+RD). We first describe the unique brain and cognitive processes involved in acquisition of math and reading skills, emphasizing similarities and differences in…

In this longitudinal study, we investigated the role of word reading and mathematical difficulties measured in 9th grade as factors for receiving educational support for learning in upper secondary education in Grades 10 to 12 (from ages 16 to 19) and furthermore as predictors of dropout from upper secondary education within 5 years after…

This study investigated the role of strategy instruction and working memory capacity (WMC) on word problem solving accuracy in children with (n = 100) and without (n = 92) math difficulties (MD). Within classrooms, children in Grades 2 and 3 were randomly assigned to one of four treatment conditions: verbal-only strategies (e.g., underlining…

Reading disability (RD) and math disability (MD) frequently co-occur, but the etiology of this comorbidity is not well understood. Groups with RD only (N = 241), MD only (N = 183), and RD + MD (N = 188) and a control group with neither disorder (N = 411) completed a battery of measures of internalizing and externalizing psychopathology, social and…

The purpose of the study was to investigate the metacognitive abilities of students with LD as they engage in math problem solving and to determine processing differences between these students and their low- and average-achieving peers (n = 73). Students thought out loud as they solved three math problems of increasing difficulty. Protocols were…

Recent studies have shown that children with mathematics difficulties (MD) have weaknesses in multiple areas of mathematics. Andersson, for example, recently found that children with MD perform significantly worse than other children on clock reading tasks. The present study builds on this recent finding and aims at a more profound understanding…

There exists a substantial number of studies that have identified a subset of low-achieving mathematics students who do not develop a reliance on retrieval for simple addition but who continue to use a counting strategy to solve these problems. There are few studies, however, that have focused on how retrieval of simple addition facts may be…

Comparison of twins (40 identical and 23 fraternal) for mathematics deficits (MD), in which at least one member had a mathematics disability, found evidence for a significant genetic etiology. However, tests for the differential etiology of MD as a function of reading performance level were nonsignificant. (Author/DB)

Siblings and parents of 39 children with dyscalculia were assessed for arithmetic, reading, and attention disorders. Findings indicated a familial prevalence of dyscalculia almost tenfold higher than expected for the general population and suggest that dyscalculia, like other learning disabilities, has a significant familial aggregation,…

This study examined whether indicators of math learning disability were observed in 35 5- and 6-year-olds with either neurofibromatosis, Turner Syndrome, or fragile X syndrome and compared to controls. Findings indicate that girls with fragile X or Turner syndrome but not neurofibromatosis are significantly more likely to have specific math…

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 examined relationships between mathematical learning difficulties (MLD) and the planning, attention, simultaneous, successive (PASS) theory of cognitive processing. PASS processes were assessed in 267 Dutch students with MLD. Results indicated students with MLD performed lower than peers on all "Cognitive Assessment System"…