Understanding Students with Disabilities · 9 min read
Characteristics of Disabilities
Intellectual Disabilities
Intellectual disability is characterized by significant limitations in intellectual functioning and adaptive behavior originating before age 18. Intellectual functioning is measured by IQ tests, with scores approximately two standard deviations below the mean (typically below 70-75) indicating limitation. Adaptive behavior encompasses conceptual skills (language, reading, money, time), social skills (interpersonal relationships, responsibility, self-esteem, following rules), and practical skills (daily living, occupational, safety).
Severity levels include mild (IQ 50-70), moderate (IQ 35-50), severe (IQ 20-35), and profound (IQ below 20). The AAIDD emphasizes support needs rather than deficit levels. With appropriate supports, individuals with intellectual disabilities can participate meaningfully in community life.
Characteristics in early childhood include delayed motor milestones, delayed speech and language, difficulty with problem-solving and reasoning, slower learning rate, limited generalization of skills, shorter attention span, and need for more repetition and practice. Social development may be relatively stronger than cognitive skills.
Educational implications include simplified language, concrete and hands-on instruction, systematic teaching with many practice opportunities, functional curriculum focus, and environmental supports.
Autism Spectrum Disorder
Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by persistent deficits in social communication and social interaction along with restricted, repetitive patterns of behavior, interests, or activities. Symptoms must be present in early childhood, though they may not fully manifest until social demands exceed capacity.
Social Communication Characteristics
Deficits range from reduced social-emotional reciprocity (limited back-and-forth conversation, reduced sharing of emotions) to difficulty developing and maintaining relationships. Nonverbal communication differences include limited eye contact, atypical facial expressions, differences in body language, and difficulty integrating verbal and nonverbal communication.
Joint attention impairments are often among the earliest signs. Children with ASD may not follow pointing, show objects of interest, or engage in shared enjoyment. Social imitation may be reduced.
Language development varies widely. Some children are nonverbal or minimally verbal, while others develop fluent speech but have pragmatic difficulties. Echolalia (repetition of heard speech) is common. Prosody (rhythm, intonation, stress) may be atypical.
Restricted and Repetitive Behaviors
Stereotyped or repetitive motor movements include hand flapping, finger flicking, body rocking, and spinning. Repetitive use of objects includes lining up toys or spinning wheels. Stereotyped or repetitive speech includes echolalia and scripted language.
Insistence on sameness manifests as extreme distress at small changes, rigid thinking patterns, ritualized behaviors, and need for predictable routines. Restricted interests are often highly intense and narrow in focus.
Sensory differences include hyper- or hypo-reactivity to sensory input. Some children seek sensory input while others avoid it. Unusual interest in sensory aspects of the environment is common.
Severity Levels
Level 1 (requiring support) involves noticeable difficulties in social communication and inflexibility causing interference in functioning. Level 2 (requiring substantial support) features marked deficits and inflexibility causing significant interference. Level 3 (requiring very substantial support) involves severe deficits and extreme inflexibility with significant distress when required to shift focus.
Co-occurring Conditions
Many individuals with ASD have intellectual disability (approximately 30-40%). Others have average to above-average intelligence. ADHD, anxiety, depression, epilepsy, sleep disorders, and feeding issues commonly co-occur.
Speech and Language Impairments
Speech Sound Disorders
Articulation disorders involve difficulty producing specific sounds correctly. Phonological disorders involve patterns of sound errors reflecting difficulty with the phonological system. Children may simplify syllable structures, substitute sounds, or omit sounds.
Motor speech disorders include childhood apraxia of speech (CAS), characterized by difficulty planning and programming motor movements for speech, and dysarthria, characterized by weakness or incoordination of speech muscles due to neurological impairment.
Fluency disorders include stuttering (disruptions in the flow of speech through repetitions, prolongations, and blocks) and cluttering (rapid, irregular speech rate with collapsed syllables).
Voice disorders involve abnormal pitch, loudness, or quality. They may result from vocal abuse, structural abnormalities, or neurological conditions.
Language Disorders
Expressive language disorder involves difficulty producing language. Children may have limited vocabulary, simplified grammar, word-finding difficulties, and trouble formulating sentences.
Receptive language disorder involves difficulty understanding language. Children may struggle following directions, understanding questions, or comprehending complex sentences.
Mixed receptive-expressive language disorder involves both comprehension and production deficits.
Specific language impairment (SLI), also called developmental language disorder (DLD), refers to language difficulties without identifiable cause such as intellectual disability, hearing loss, or autism.
Social (pragmatic) communication disorder involves persistent difficulties in the social use of verbal and nonverbal communication. Unlike ASD, there are no restricted or repetitive behaviors.
Hearing Impairments
Hearing loss is measured in decibels (dB). Mild loss (26-40 dB) causes difficulty hearing soft speech. Moderate loss (41-55 dB) causes difficulty with conversational speech. Moderately severe loss (56-70 dB) requires amplification for most speech. Severe loss (71-90 dB) makes hearing speech without amplification extremely difficult. Profound loss (>90 dB) means hearing is not functional for speech perception.
Types include conductive (outer or middle ear), sensorineural (inner ear or auditory nerve), and mixed. Sensorineural losses are generally permanent while conductive losses may be medically treatable.
Onset may be congenital or acquired. Prelingual hearing loss (before language development) has greater impact on spoken language than postlingual loss. Etiology includes genetic factors, prenatal infections (CMV, rubella), prematurity, ototoxic medications, meningitis, and chronic ear infections.
Communication approaches include auditory-oral (emphasis on listening and spoken language with amplification), total communication (combination of oral and manual methods), and bilingual-bicultural (ASL as primary language with English as second language). Cochlear implants may be appropriate for children with severe to profound sensorineural loss who receive limited benefit from hearing aids.
Visual Impairments
Legal blindness is defined as visual acuity of 20/200 or less in the better eye with correction, or visual field of 20 degrees or less. Low vision refers to visual impairment not correctable by standard glasses, contacts, or medical treatment that interferes with daily activities.
Types include refractive errors (myopia, hyperopia, astigmatism), disorders of the eye structures (cataracts, glaucoma), retinal conditions (retinopathy of prematurity, retinal detachment), and cortical visual impairment (brain-based visual processing difficulties).
Impact on development includes limited incidental learning, delayed motor development due to reduced motivation to reach and explore, concept development challenges (understanding concepts typically learned visually), and need for explicit instruction in skills typically learned through observation.
Educational implications include tactile learning materials, braille literacy when appropriate, orientation and mobility training, use of residual vision, assistive technology, and modifications to the physical environment.
Physical and Health Impairments
Cerebral Palsy
Cerebral palsy (CP) is a group of permanent movement disorders resulting from non-progressive brain injury occurring before, during, or shortly after birth. Types include spastic (most common, characterized by stiff muscles), dyskinetic (involuntary movements), ataxic (balance and coordination difficulties), and mixed.
Distribution patterns include hemiplegia (one side of body), diplegia (primarily legs), and quadriplegia (all four limbs). Severity ranges from mild motor difficulties to complete dependence for mobility and self-care.
Associated conditions may include intellectual disability (though many have typical intelligence), epilepsy, visual and hearing impairments, speech difficulties, feeding challenges, and orthopedic complications.
Other Motor Impairments
Spina bifida results from incomplete closure of the neural tube during fetal development. Severity depends on location and type (myelomeningocele being most severe). Effects may include paralysis, sensory loss, bladder and bowel dysfunction, and hydrocephalus.
Muscular dystrophy involves progressive muscle weakness. Duchenne muscular dystrophy, the most common childhood form, primarily affects boys and typically results in loss of ambulation by early adolescence.
Health Impairments
Chronic health conditions affecting educational participation include asthma, diabetes, epilepsy, cancer, HIV/AIDS, sickle cell disease, and cystic fibrosis. Children may experience fatigue, frequent absences, medication side effects, and need for specialized health procedures at school.
Emotional and Behavioral Disorders
Emotional disturbance under IDEA includes conditions exhibiting one or more characteristics over a long period of time and to a marked degree that adversely affects educational performance: inability to learn not explained by intellectual, sensory, or health factors; inability to build or maintain satisfactory relationships with peers and teachers; inappropriate behaviors or feelings under normal circumstances; pervasive mood of unhappiness or depression; and tendency to develop physical symptoms or fears associated with personal or school problems. The term includes schizophrenia but does not include children who are socially maladjusted unless they also have an emotional disturbance.
Internalizing Behaviors
Anxiety disorders include generalized anxiety, separation anxiety, social anxiety, specific phobias, and selective mutism. Symptoms include excessive worry, physical symptoms (stomachaches, headaches), avoidance, and difficulty with transitions.
Depression in young children may manifest as irritability, withdrawal, decreased interest in activities, changes in sleep and appetite, low self-esteem, and sometimes regressive behaviors.
Externalizing Behaviors
Attention-deficit/hyperactivity disorder (ADHD) involves persistent patterns of inattention and/or hyperactivity-impulsivity that interfere with functioning or development. Presentations include predominantly inattentive, predominantly hyperactive-impulsive, and combined.
Oppositional defiant disorder (ODD) involves a pattern of angry/irritable mood, argumentative/defiant behavior, and vindictiveness. Conduct disorder involves persistent patterns of behavior violating the basic rights of others or major age-appropriate societal norms.
Trauma and Adverse Childhood Experiences
Early trauma and adverse childhood experiences (ACEs) can have profound effects on brain development and functioning. Effects include hypervigilance, difficulty regulating emotions, attachment difficulties, learning challenges, and increased risk for mental health conditions. Trauma-informed approaches recognize the impact of trauma and avoid re-traumatization.
Multiple Disabilities and Deaf-Blindness
Multiple disabilities refers to concomitant impairments that cause severe educational needs not accommodated by programs for any single impairment. Deaf-blindness is a separate category involving combined hearing and visual impairments causing severe communication and other developmental and educational needs.
Children with multiple disabilities often have complex medical needs, require support across all developmental domains, and need highly individualized programming. Communication systems must be developed based on individual sensory, motor, and cognitive abilities.
Learning Disabilities
Specific learning disabilities involve disorders in one or more basic psychological processes involved in understanding or using language, spoken or written, that may manifest in imperfect ability to listen, think, speak, read, write, spell, or do mathematical calculations. The term includes conditions such as perceptual disabilities, brain injury, minimal brain dysfunction, dyslexia, and developmental aphasia. It does not include learning problems primarily resulting from visual, hearing, or motor disabilities; intellectual disability; emotional disturbance; or environmental, cultural, or economic disadvantage.
In early childhood, precursors to learning disabilities may be observed, including phonological awareness difficulties, trouble learning letter names and sounds, difficulty with rhyming, limited vocabulary, poor memory for sequences, and difficulty following multi-step directions.
Dyslexia
Dyslexia is a specific learning disability characterized by difficulties with accurate and fluent word recognition, poor spelling, and decoding abilities. It typically results from a deficit in the phonological component of language. Early signs include difficulty with rhyming, trouble learning letter names and sounds, and difficulty manipulating sounds in words.
Dyscalculia
Dyscalculia involves difficulties with number sense, memorizing arithmetic facts, accurate calculation, and mathematical reasoning. Early signs include difficulty learning to count, trouble recognizing quantities, and challenges understanding number relationships.
Dysgraphia
Dysgraphia involves difficulties with handwriting, spelling, and putting thoughts on paper. It may involve motor-based difficulties with letter formation and/or language-based difficulties with written expression.
Developmental Delay
Developmental delay is a category available for children ages 3-9 (or subset determined by states) who experience delays in one or more developmental domains: physical, cognitive, communication, social-emotional, or adaptive. This category allows services without requiring a specific disability diagnosis, which may be difficult or inappropriate to determine in young children.
Delay is typically defined as functioning significantly below age expectations, often 1.5 to 2 standard deviations below the mean or 25-33% below chronological age. States define specific criteria within federal parameters.
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