The Profiles and Patterns of Progress in Numerical Skills of Elementary School Students with Mild and Moderate Intellectual Disability

The purpose of this study was to identify the different profiles and patterns of progress in numerical skills of 6- to 10-year-old elementary school students with mild or moderate intellectual disability (ID). A standardised test of numerical and arithmetic skills was administered to 57 students with ID at the beginning and at the end of a school year. A cluster analysis was conducted with the participants' numerical skills at Time 1 and Time 2. Four groups of children which exhibited significantly distinct profiles at the beginning of the school year were identified: (1) children with inconsistent basic numerical skills with numbers up to 10, (2) children with basic numerical skills with numbers up to 10, (3) children with numerical skills with numbers up to 20, (4) children with numerical skills with numbers up to 100 and arithmetic skills. The group of children with inconsistent basic numerical skills with numbers up to 10 did not progress significantly during the school year. In contrast, most children with the second, third and fourth profile extended their numerical skills to larger number domains (respectively up to 20, 100 or 1000) during the school year. The implications of these findings are discussed.