Intellectual Disability


Intellectual disability occurs before age 18, and is characterized by delayed development in intellectual functioning and adaptive behavior. The intellectual disability may vary from mild to profound. Adaptive behavior includes skills that people learn so that they can function in their everyday lives. This delayed development is reflected in low performance across academic and other skill areas, as well as significantly lower scores on measures of intelligence and adaptive behavior, when compared with students who are not identified with intellectual disabilities.

Depending on the local school district, criteria for Intellectual Disability eligibility will often require that the child is about 2-4 years behind, or has an IQ below 70-75. A score of approximately 70 or below in an intelligence test is considered to be “below average” intellectual functioning.  Students with intellectual disabilities have a measured IQ that is lower than 98% of the school-age population. A standardized test of adaptive behavior is used to determine if the child has deficits in conceptual, social, and practical skills that are significantly below average.

Intellectual Functioning
  • 2-4 years behind in all areas of cognitive development (e.g. reasoning, problem-solving, working memory)
  • Low achievement in most or all academic areas (e.g. reading comprehension, mathematics, written expression)
  • Short attention span and easily distractible
  • Delays in speech development
  • May not be confident in school and is easily frustrated
  • Difficulties with learning concepts
  • Academic difficulties last across the school years
  • May seem to learn more slowly than do other students
  • Difficulty with working memory tasks (e.g. math facts or spelling words)
  • May seem to remember information one day, and forget it the next
  • Difficulty using academic strategies (e.g. note taking, memorizing definitions)
  • Difficulty with generalization of information to other material
  • Difficulty generalizing material learned in one setting to another (e.g., from school to the community)
  • Difficulties with more advanced academic skills related to content (e.g. math word problems, identifying themes and symbols in literature)
  • Delays in language may affect reading
  • May have difficulty comprehending and summarizing what has been read
  • Weak vocabulary (knowledge of words)
  • May operate at a concrete rather than abstract level of thinking

Adaptive Behavior (communication, socialization, daily living, behavior) 
  • Difficulty bathing, dressing, grooming, and / or feeding one’s self
  • Language may be slow to develop
  • Speech may be delayed, or there may be no speech at all
  • Difficulty understanding and using language (verbal and nonverbal)
  • Social skills may be poor (relationships with family and friends)
  • May misinterpret the intentions of others
  • May not understand how to pay for things
  • May lack understanding of personal safety or community navigation issues
  • Has trouble linking actions to consequences
  • May be clumsy
  • May use simple language with short sentences
  • May need reminders about hygiene - washing hands, brushing teeth, etc.
  • Exhibits problem behaviors and some immaturity
  • Displays some obsessive / compulsive behaviors
  • Difficulty following rules and routines

Categories of mild, moderate, severe and profound levels of intellectual disability are defined on the basis of IQ scores. Some students will require greater support than others will.

Mild Intellectual Disability
A mild intellectual disability is defined as an IQ between 50 and 70.

  • Can independently participate in most leisure activities within their communities
  • Will have important relationships with the people in their life
  • May struggle in certain social situations
  • May marry and raise a family with support
  • May have a job suited to their skills
  • May live and travel independently with  support
  • May need help to handle money and to plan and organize their daily routine
  • May learn to read and write in appropriate educational setting
  • Likely to develop reading, writing, and math skills at a basic level

Moderate Intellectual Disability
A moderate intellectual disability is defined as an IQ between 35 and 50.

  • Will have important relationships with the people in their life
  • May learn to navigate their community and travel with support
  • Will have difficulty planning trips and handling money independently
  • Will recognize environmental print (e.g. signs, logos, sight words) in daily life
  • Will need visual prompts such as daily schedules and pictures of routines
  • Will need support in their daily lives
  • May display independence in certain daily living activities, such as dressing and bathing

Severe or Profound Intellectual Disability
A severe intellectual disability is defined as an IQ between 20 and 35. A profound intellectual disability is defined as an IQ below 20.

  • Will have important relationships with the people in their life
  • May have little or no speech and will rely on gestures, facial expressions, and body language to communicate needs or feelings
  • Will require functional communication systems (e.g. low or high tech augmentative communication devices) in order to express their wants and needs
  • Will need visual prompts such as daily schedules and pictures of routines
  • Will require extensive support with daily living activities throughout their life

Strategies for Intellectual Disability