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02.01 — IDEA Overview for Paras

• Before EHA, about 1 million U.S. children with disabilities were shut out of public schools

  Congress's own findings in IDEA

  20 U.S.C. §1400(c) — the statute states the figure about the era it was passed to end

04.05 — Reinforcement Basics

• There is no research-backed number for the positive-to-corrective ratio — the direction is supported, the figure is not

  Sabey, Charlton and Charlton, Journal of Emotional and Behavioral Disorders 2019

  Reviewing the ratio literature directly: the rule has good face validity but lacks empirical support for any specific number. The brief previously stated 4:1 as a research finding.

05.18 — PBIS and the Para's Role

• CICO is the most-studied Tier 2 intervention, with mixed rather than uniformly strong support

  Maggin and colleagues, Journal of Positive Behavior Interventions 2015

  A systematic evidence review; effects vary with behaviour function and implementation fidelity

07.01 — Autism

• Autism at about 1 in 31 U.S. children

  CDC, Autism and Developmental Disabilities Monitoring Network

  2022 surveillance year, published 2025

• 39.6% of identified autistic children had an intellectual disability

  CDC ADDM Network

  Ranged 31.2%–52.8% depending on the group of children looked at

• Epilepsy about 21.5% where intellectual disability is present, about 8% where it is not

  Amiet and colleagues, meta-analysis

  Pools 10 studies published through 2006

Anxiety and ADHD co-occurrence carry no figure. Published ranges run 0–82% and 0–86%; no authority states a tighter one, so the brief says the conditions co-occur and stops there.

07.02 — ADHD

• The 20,000-additional-critical-messages-by-age-10 figure is a clinician's estimate, not a study

  Attributed in the popular literature to William Dodson, MD

  No peer-reviewed source states it; the brief previously credited it to Russell Barkley's research

07.04 — Dyslexia

• About 3–7% at a criterion of 1.5 standard deviations below the mean

  Fletcher et al. 2019; Peterson & Pennington 2012; Snowling & Melby-Lervåg 2016

• 17.4% at a 25th-percentile cut

  Shaywitz and colleagues, 1992

• Dyslexia lasts into adult life

  International Dyslexia Association

The widely-repeated “5–17%” figure is not the IDA's, though much of the web attributes it there — the IDA's own page gives 15–20% for language-based learning disabilities, a broader category. The brief states the range as what it is: an artefact of where the cut-off is set.

07.05 — Intellectual Disability

• IQ about 2 standard deviations below the mean; onset before age 22

  American Association on Intellectual and Developmental Disabilities

  The before-22 developmental-period rule is AAIDD's 2021 revision, up from 18

07.06 — Emotional Disturbance (EBD)

• No research-backed number for the positive-to-corrective ratio

  Sabey, Charlton and Charlton, Journal of Emotional and Behavioral Disorders 2019

  Good face validity, no empirical support for any specific ratio. The brief previously called 4:1 well-evidenced, crediting Sprick et al.

07.07 — Speech and Language Impairment

• About 1% of people stutter

  National Institute on Deafness and Other Communication Disorders

07.08 — Down Syndrome

• About 1 in 700 U.S. births

  CDC

• Trisomy 21 about 95%, translocation about 3%, mosaicism about 2%

  National Down Syndrome Society

• Heart defects from birth 40–50%; some hearing loss about 75%; sleep apnea 50–79%

  American Academy of Pediatrics

  Health Supervision for Children and Adolescents With Down Syndrome, 2022

The CDC and the National Down Syndrome Society count occurrence differently — 1 in 700 against 1 in 775 as of 2018. Both are current. The brief uses the CDC's and says so rather than silently picking one.

07.09 — Cerebral Palsy

• About 1 in 345 children

  CDC ADDM cerebral-palsy tracking

  2010 surveillance — the most recent the CDC has published

• Epilepsy about 42% of identified children

  CDC ADDM cerebral-palsy tracking

  2010 surveillance

Vision, hearing and speech co-occurrence carry no figures: no US authority states them.

07.11 — Deaf and Hard of Hearing

• More than 90% of Deaf children are born to hearing parents

  National Institute on Deafness and Other Communication Disorders

07.12 — Visual Impairment

• Low vision: acuity 20/70 or poorer, not correctable with regular glasses

  American Foundation for the Blind

• Legally blind: 20/200 or less, or a visual field of 20 degrees or less

  American Foundation for the Blind

• 41% of working-age adults with vision difficulty in paid work, against 72% without

  Current Population Survey 2023, via the American Foundation for the Blind

07.14 — Tourette Syndrome

• Coprolalia in a minority — roughly 1 to 2 in 10

  Tourette Association of America

• ADHD about 60%; OCD figures likewise

  Tourette Association of America

  Both from clinic samples; whole-population rates run markedly lower

The brief says so in the text: a para who expects the clinic rate in a classroom will over-expect.

07.15 — Anxiety Disorders

• 31.9% of adolescents have had any anxiety disorder

  National Institute of Mental Health

  Lifetime prevalence, National Comorbidity Survey Adolescent Supplement

This brief previously said “about 1 in 10 by their teens” — an understatement of roughly three times, in the direction that makes a para less likely to expect anxiety in the students in front of them. It had passed a careful human read: a figure is not checkable by reading closely, only by opening the source.

07.18 — Selective Mutism

• Around 0.5%–1% of children

  School-based and clinic prevalence studies

  Published estimates range 0.2%–1.9% by setting and age

07.20 — Fetal Alcohol Spectrum Disorder

• 1 in 100 to 1 in 20 first-graders

  May and colleagues, JAMA 2018

  Conservative range across four US communities

• Fetal alcohol syndrome can be diagnosed without a confirmed exposure history; partial FAS only under the Revised IOM guideline

  Comparison of the five current FASD diagnostic guidelines

  The other four guidelines require confirmed exposure for partial FAS

15.07 — Poverty and Schooling

• The size of the early vocabulary-exposure gap is disputed

  Sperry, Sperry and Miller, Child Development 2019; reply by Golinkoff and colleagues

  Five communities; a far smaller gap when all speech heard is counted rather than only child-directed speech. Hart and Risley's original figure rests on 42 families