Understanding Students with Disabilities: Categories, Definitions, and Causes
Know the categories, not just the labels
IDEA recognizes thirteen disability categories, and questions reward precise knowledge of the definitional hinge inside each one rather than the label alone. Four high-incidence categories - specific learning disability, speech or language impairment, intellectual disability, and emotional disturbance - account for the majority of students served. Low-incidence categories include deaf-blindness, traumatic brain injury, visual impairment including blindness, hearing impairment and deafness, orthopedic impairment, other health impairment, autism, multiple disabilities, and developmental delay (a state-optional category typically used through age nine).
Specific learning disability is a disorder in basic psychological processes that manifests in the imperfect ability to listen, think, speak, read, write, spell, or calculate. Dyslexia, dysgraphia, and dyscalculia are manifestations of SLD, not separate categories. The definition contains exclusionary criteria: a learning problem caused primarily by visual, hearing, or motor disability, intellectual disability, emotional disturbance, or environmental, cultural, or economic disadvantage is not SLD. ADHD is served under other health impairment (limited strength, vitality, or alertness, including heightened alertness to environmental stimuli) - it has no category of its own. Intellectual disability requires significantly subaverage intellectual functioning together with concurrent deficits in adaptive behavior, manifesting during the developmental period. Emotional disturbance requires one or more of five characteristics over a long period and to a marked degree that adversely affects educational performance; the definition specifically excludes students who are socially maladjusted unless another criterion is met. Autism is generally evident before age three and affects verbal and nonverbal communication and social interaction.
Trap: prevalence questions. SLD and speech-language are the two largest groups; candidates routinely overestimate intellectual disability and underrate speech-language.
Rule of thumb: if the stem explains school failure by attendance, limited English proficiency, or lack of appropriate instruction, ask the exclusionary-criteria question before naming a disability.