ABSTRACT
Hallahan and Mercer suggest five important periods in the historical evolution of specific learning disabilities (SLD): Foundation Period in Europe; Foundation Period in United States; Emergent Period; Solidification Period; and Turbulent Period. At present, there are a number of different definitions of SLD offered by various organizations and systems in the United States that have evolved over the years: Diagnostic and Statistical Manual of Mental Disorders, the Individuals with Disabilities Education Improvement Act, 2004, the National Joint Committee for Learning Disabilities, association for children with learning disabilities (ACLD)/ learning disabilities association (LDA), and interagency committee on learning disabilities (ICLD). Dyslexia is the most prevalent type of SLD, occurring in an estimated 5" to 17.5" of school-age children. The two primary conditions associated with primary mathematics learning disabilities (MLD) are underachievement in math that may be related to deficits due to other verbal learning disabilities, and/or dyscalculia.
