Early Numerical Competencies of Students with Different Forms of Mathematics Difficulty.

The purpose of the study was to examine differences in early numerical competencies, as well as subtraction skill, as a function of children's mathematics difficulty (MD) status: computational difficulty (CD), word problem-solving difficulty (PD), concurrent difficulty (CDPD), or neither difficulty (i.e., typically developing; TYP). Based on measures of addition and word-problem skill, second grade students (N = 332) were classified in terms of MD status. Then, students were assessed on three early numerical competency measures (Number Line Estimation, Number Sets Test, and Counting Knowledge) as well as a measure of subtraction. On Number Line Estimation and Number Sets Test, students with CD and those with PD scored comparably, but both outperformed students with CDPD. On Counting Knowledge-Double First, students with CDPD scored lower than the three contrasting groups. On subtraction, students with CD outperformed those with PD, and students with PD and those with CDPD performed comparably. Findings are discussed in terms of differential performance as a function of difficulty status and implications for understanding and teaching subtypes of MD.