1.2 Specific Learning Disabilities (SLD) and ADHD

Specific Learning Disabilities (SLD) Criteria and Manifestations

Under federal regulations (34 CFR § 300.8(c)(10)) and Illinois Administrative Code (23 IL Admin Code 226.750), a Specific Learning Disability (SLD) is defined as 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 do mathematical calculations.

SLD does not include learning problems that are primarily the result of visual, hearing, or motor disabilities, intellectual disability, emotional disturbance, or environmental, cultural, or economic disadvantage. SLD encompasses three major clinical manifestations:

1. Dyslexia (Reading-Based SLD)

Dyslexia is a neurodevelopmental disorder characterized by difficulties with accurate and/or fluent word recognition, poor decoding skills, and poor spelling. It stems primarily from a core deficit in the phonological component of language (phonological awareness, phonemic segmentation, and orthographic mapping). Secondary consequences include reading comprehension difficulties and reduced reading background knowledge.

• Evidence-Based Interventions: Structured Literacy approaches incorporating explicit, systematic, multi-sensory instruction in phonemic awareness, synthetic phonics, morphology, and fluency (e.g., Orton-Gillingham, Wilson Reading System).

2. Dyscalculia (Mathematics-Based SLD)

Dyscalculia involves severe impairment in learning mathematical concepts, number sense, arithmetic fact retrieval, and quantitative reasoning. Students struggle with subitizing (instantly recognizing the quantity of a small group of objects without counting), understanding place value, executing multi-step math algorithms, and visual-spatial representations of math relationships.

• Evidence-Based Interventions: The Concrete-Representational-Abstract (CRA) instructional sequence, explicit instruction in math vocabulary, visual number lines, touch-point math, and schema-based instruction for word problems.

3. Dysgraphia (Written Expression SLD)

Dysgraphia manifests as significant impairment in written expression, encompassing graphomotor mechanics (handwriting execution, fine motor planning, pencil grasp), orthographic coding (spelling accuracy), and sentence structure composition.

• Evidence-Based Accommodations & Interventions: Speech-to-text software, graphic organizers, visual word banks, slant boards, adaptive pencil grips, and explicit handwriting programs (e.g., Handwriting Without Tears).

Identification Models: Severe Discrepancy vs. RTI / MTSS Dual Discrepancy

Historically, school systems identified SLD using the Severe Discrepancy Model. This legacy model required demonstrating a statistically significant gap (typically 1.5 to 2 standard deviations, or 15–22 points) between a student's standardized Full Scale Intelligence Quotient (IQ) score and their achievement scores on standardized tests (e.g., WIAT, WJ-IV).

Flaws of the Severe Discrepancy Model

• Wait-to-Fail Paradigm: Young children in kindergarten through 2nd grade rarely demonstrate a large enough discrepancy to qualify for services, forcing schools to wait until academic deficits worsen severely in 3rd or 4th grade.
• Assessment Bias: Standardized IQ tests can reflect cultural, linguistic, or socio-economic biases rather than underlying learning aptitude.
• Lack of Instructional Utility: IQ testing does not yield direct diagnostic information for designing daily academic interventions.

Modern RTI / MTSS Identification Model

With the reauthorization of IDEA in 2004 and ISBE regulations (23 IL Admin Code 226.750), Illinois districts are authorized to utilize Multi-Tiered System of Supports (MTSS) and Response to Intervention (RTI) data to establish SLD eligibility. MTSS structures instruction into three progressive tiers:

• Tier 1 (Universal Core Instruction): High-quality, evidence-based core instruction provided to all students in general education classrooms (~80–85% of students respond successfully). Universal screening occurs 3 times per year.
• Tier 2 (Targeted Intervention): Supplemental, small-group evidence-based interventions provided to students identified as at-risk (~10–15% of students). Progress is monitored bi-weekly using Curriculum-Based Measurement (CBM).
• Tier 3 (Intensive Individualized Intervention): High-intensity, individualized interventions delivered in smaller group sizes or longer durations (~3–5% of students). Progress is monitored weekly.

To qualify for SLD under RTI, the multidisciplinary evaluation team must document a Dual Discrepancy:

1. Performance Level Discrepancy: The student's academic performance level is significantly below grade-level benchmarks compared to age/grade peers.
2. Rate of Growth (Slope) Discrepancy: The student's rate of academic growth (slope of improvement on CBM progress monitoring charts) remains insufficient to close the achievement gap, even when provided with high-fidelity, evidence-based Tier 2 and Tier 3 interventions.

Executive Functioning Deficits in SLD and ADHD

Executive Functioning (EF) refers to the cognitive control processes coordinated primarily by the prefrontal cortex that enable goal-directed behavior. Executive dysfunction is a core feature shared by students with SLD and Attention-Deficit/Hyperactivity Disorder (ADHD).

Primary Executive Function Domains

• Working Memory: The capacity to temporarily hold and manipulate information in consciousness (e.g., holding a multi-step math word problem in mind while performing calculation steps). Working memory comprises the phonological loop (verbal storage), visuospatial sketchpad (visual/spatial storage), and central executive (attentional allocation).
• Response Inhibition: The ability to resist impulses, stop inappropriate responses, and suppress distractions.
• Cognitive Flexibility (Set-Shifting): The ability to switch attention between tasks, adjust to changing rules or unexpected schedule changes, and consider alternative perspectives.
• Planning and Organization: The capacity to break long-term projects into sequential steps, estimate time, prioritize tasks, and maintain organized materials.
• Self-Monitoring (Metacognition): The ability to evaluate one's own academic performance and behavioral output in real-time, detecting errors and applying corrective strategies.

ADHD Subtypes and IDEA Eligibility

Under the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition), Attention-Deficit/Hyperactivity Disorder (ADHD) is classified into three distinct presentations:

1. Predominantly Inattentive Presentation: Characterized by failure to pay close attention to details, persistent careless mistakes, difficulty sustaining focus, appearing not to listen when spoken to directly, disorganization, losing necessary materials, distractibility, and forgetfulness.
2. Predominantly Hyperactive-Impulsive Presentation: Characterized by frequent fidgeting, squirming, leaving seat in classrooms, excessive running or climbing, difficulty engaging in quiet activities, feeling "driven by a motor," excessive talking, blurting out answers before questions are completed, difficulty awaiting turns, and interrupting others.
3. Combined Presentation: Criteria for both inattention and hyperactivity-impulsivity are met for the past 6 months.

Diagnostic & Legal Requirements for ADHD

To meet DSM-5 diagnostic criteria, symptoms must:

• Persist for at least 6 months to a degree inconsistent with developmental level.
• Be present prior to age 12.
• Be present in two or more settings (e.g., home and school).
• Significantly interfere with academic, social, or occupational functioning.

In public school special education under IDEA, ADHD is not a standalone eligibility category. Instead, students with ADHD who require specialized instruction are determined eligible under the category of Other Health Impairment (OHI) because the condition causes limited alertness (or heightened alertness to environmental stimuli) that adversely affects educational performance. If a student's ADHD causes academic impact but does not require specialized instruction (IEP), the student may receive classroom accommodations under a Section 504 Plan.