evidence: Specific Learning Disability (SLD) Under IDEA, "Specific Learning Disability (SLD) means a disorder in one or more of the basic psychological processes involved in understanding or in using language, spoken or written, that may manifest itself in the imperfect ability to listen, think, speak, read, write, spell, or to do mathematical calculations, including conditions such as perceptual disabilities, brain injury, minimal brain dysfunction, dyslexia, and developmental aphasia. Specific learning disability does not include learning problems that are primarily the result of visual, hearing, or motor disabilities, of mental retardation, of emotional disturbance, or of environmental, cultural, or economic disadvantage" (34 C.F.R. Section 300.8(c)(10)). Dyslexia is a subcategory of Specific Learning Disability (SLD) and has been added so that the Department can distinguish students with dyslexia from other students with SLD who are reported in this disability category.