8.2 Multi-Tiered System of Supports (MTSS) and RTI Tiers 1, 2, and 3

8.2 Multi-Tiered System of Supports (MTSS) and RTI Tiers 1, 2, and 3

GACE Blueprint Focus: Objective 0006 assesses an educator's mastery of the Multi-Tiered System of Supports (MTSS) and Response to Intervention (RTI) frameworks; the three-tier instructional continuum (Tier 1 core, Tier 2 targeted supplemental, Tier 3 intensive individualized); intervention fidelity; Curriculum-Based Measurement (CBM) progress monitoring; and the psychometric principles of the Dual-Discrepancy Model for data-based decision-making.

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MTSS and RTI Architecture: Foundations and Philosophy

Historically, the identification of students with learning disabilities in American public education relied upon the IQ-Achievement Discrepancy Model. Under this outdated psychometric model, a student could only qualify for specialized reading intervention if a statistically significant gap (typically 1.5 to 2 standard deviations) existed between their measured Full-Scale IQ score and their standardized academic achievement score. In practice, this created a devastating "wait-to-fail" syndrome: young struggling readers in Kindergarten, first grade, and second grade rarely exhibited a large enough statistical discrepancy to qualify for help. By the time their academic failure was severe enough in fourth or fifth grade to trigger services, the neurobiological window for optimal reading remediation had closed, and secondary emotional and behavioral consequences had taken root.

To eradicate the wait-to-fail model, the 2004 reauthorization of the Individuals with Disabilities Education Act (IDEA) permitted states and school districts to use a scientific, data-driven alternative known as Response to Intervention (RTI). In Georgia, RTI is integrated within the broader umbrella framework of the Multi-Tiered System of Supports (MTSS) (codified under Georgia State Board of Education Rule 160-4-2-.32). MTSS is a comprehensive, school-wide prevention framework that systematically addresses academic, behavioral (PBIS), and social-emotional needs through escalating tiers of evidence-based instruction and intervention.

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|               THE THREE-TIER CONTINUUM OF MTSS / RTI                    |
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|                                                                         |
|                         /\                                              |
|                        /  \                                             |
|                       / T3 \        TIER 3: Intensive Individualized    |
|                      / ~3-5%\       - 1-3 students; 45-60 min daily     |
|                     /--------\      - Weekly CBM progress monitoring    |
|                    /  TIER 2  \                                         |
|                   /  ~10-15%   \    TIER 2: Targeted Supplemental       |
|                  /--------------\   - 3-5 students; 30 min, 3-4x/week   |
|                 /    TIER 1      \  - Bi-weekly CBM progress monitoring |
|                /    ~80-85%       \                                     |
|               /  (100% of Pupils)  \ TIER 1: Universal Core Reading    |
|              +----------------------+ - High-quality, evidence-based    |
|                                       - Universal screening 3x/year     |
+-------------------------------------------------------------------------+

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The Three-Tier Continuum: Structural Specifications

The MTSS continuum is organized into three distinct, interconnected tiers of instructional intensity. Movement between tiers is governed strictly by empirical student assessment data.

Tier 1: High-Quality Universal Core Instruction

• Target Population: Provided to 100% of students in general education classrooms.
• Instructional Focus: High-quality, scientifically validated, research-based core literacy instruction aligned with the Georgia Standards of Excellence (GSE). Tier 1 instruction must explicitly integrate all five essential components of reading: phonological awareness, phonics, fluency, vocabulary, and text comprehension.
• Efficacy Benchmark: In a healthy, well-functioning school system, Tier 1 instruction should successfully meet the literacy development needs of approximately 80% to 85% of the student population without supplemental intervention.
• Assessment Cadence: All students undergo Universal Screening three times per year (Fall/Benchmark 1, Winter/Benchmark 2, Spring/Benchmark 3) using validated, brief, standardized screening tools (such as DIBELS 8th Edition or Acadience Reading).
• Differentiation: Tier 1 includes within-class small-group differentiated instruction provided by the general education teacher to support varied learning needs.

Tier 2: Targeted Supplemental Small-Group Intervention

• Target Population: Serves approximately 10% to 15% of students identified as "at risk" or performing below established benchmark cut-scores on universal screening assessments.
• Instructional Delivery: Tier 2 intervention is delivered in homogeneous small groups of 3 to 5 students who share similar, specific skill deficits (e.g., short vowel decoding or phoneme segmentation).
• Dosage & Frequency: Typically administered for 30 minutes per session, 3 to 4 days per week, in addition to standard Tier 1 core instruction.
• Provider: Delivered by general education teachers, specialized reading interventionists, or certified specialists trained in targeted intervention protocols.
• Curricular Design: Standardized, scripted, evidence-based intervention programs that target specific foundational reading gaps (e.g., an intensive phonological awareness protocol or targeted multisyllabic decoding routine).
• Progress Monitoring Cadence: Student progress is formally monitored bi-weekly (every two weeks) using standardized Curriculum-Based Measurement (CBM) probes to track skill acquisition and growth rate.

Tier 3: Intensive Individualized Intervention

• Target Population: Serves approximately 3% to 5% of students who demonstrate persistent, severe academic deficits and who have failed to make adequate progress despite receiving high-fidelity Tier 2 interventions.
• Instructional Delivery: Highly individualized, clinical instruction delivered in very small groups of 1 to 3 students or 1-on-1.
• Dosage & Frequency: Intensive daily sessions lasting 45 to 60 minutes, 5 days per week.
• Provider: Highly trained reading specialists, dyslexia specialists, or special education interventionists.
• Curricular Design: Highly explicit, systematic, multisensory Structured Literacy curricula tailored to the student's unique diagnostic profile. Instruction breaks linguistic concepts down into fine-grained sub-skills with increased opportunities for student response and feedback.
• Progress Monitoring Cadence: Formal progress monitoring is conducted weekly using standardized CBM probes to ensure immediate detection of instructional efficacy.

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The Ironclad Rule: Interventions Must Supplement, Never Supplant Core Instruction

A critical, frequently tested mandate of MTSS is the supplemental principle:

[!IMPORTANT] Interventions Supplement Core Instruction: Tier 2 and Tier 3 interventions must never supplant (replace) Tier 1 core reading instruction.

Pulling a struggling reader out of the general education 90-minute literacy block to receive Tier 2 or Tier 3 phonics instruction creates an insurmountable instructional deficit. While the student receives remediation on phonics, they miss Tier 1 instruction in vocabulary, background knowledge, literary analysis, and grade-level comprehension standards. Consequently, the achievement gap widens rather than closes. Schools must structure master schedules so that Tier 2 and Tier 3 intervention blocks occur during dedicated "intervention and enrichment" (WIN - "What I Need") periods, outside of the protected universal core literacy block.

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Fidelity of Implementation: The Prerequisite for Data Validity

In the MTSS framework, a student cannot be identified as having a learning disability or deemed an "intervention non-responder" unless the school can prove fidelity of implementation. Fidelity means that the intervention was delivered precisely as designed, validated, and scheduled by the curriculum developers and MTSS plan.

Fidelity comprises four distinct dimensions:

1. Adherence: Was the intervention delivered following the specific pedagogical procedures, explicit scripts, and lesson sequences of the evidence-based program without unauthorized omissions?
2. Dosage (Exposure): Did the student receive the prescribed amount of intervention time (e.g., 30 minutes per day, 4 days per week for 10 weeks)? If the student or interventionist was repeatedly absent, dosage was compromised.
3. Quality of Delivery: Did the interventionist demonstrate high-quality explicit modeling, maintain appropriate pacing, and deliver accurate, immediate corrective feedback?
4. Student Engagement: Was the student actively attending, responding, and participating during the intervention sessions?

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|                 THE FOUR DIMENSIONS OF INTERVENTION FIDELITY            |
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|                                                                         |
|   [ ADHERENCE ]       --> Curriculum delivered exactly as designed;     |
|                           no skipping core routines or steps            |
|                                                                         |
|   [ DOSAGE ]          --> Complete minutes and sessions completed;      |
|                           attendance logs verify exposure               |
|                                                                         |
|   [ QUALITY ]         --> Skilled teacher modeling, brisk pacing,       |
|                           and immediate corrective feedback             |
|                                                                         |
|   [ ENGAGEMENT ]      --> Student actively on-task, responding to       |
|                           prompts, and completing practice trials       |
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|  CRITICAL RULE: If fidelity is compromised, a lack of student progress  |
|  reflects INSTRUCTIONAL FAILURE, not a student learning disability!     |
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If a school team convenes to review a student's lack of progress and discovers that the interventionist only met with the group twice a week instead of four times, or skipped the phonemic blending drills to do unapproved coloring sheets, the data is invalid. The student cannot be moved to Tier 3 or referred for special education evaluation. The intervention must first be implemented with documented fidelity.

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The Dual-Discrepancy Model: Making Data-Based Placement Decisions

To eliminate subjective teacher bias and ensure equitable placement decisions, MTSS relies on the Dual-Discrepancy Model (Fuchs, Fuchs, & Speece). Under this psychometric model, a student's response to intervention is judged using two independent, objective criteria:

1. Discrepancy in Performance Level: How far below the expected grade-level benchmark is the student's absolute score? (Where is the student currently performing?)
2. Discrepancy in Rate of Improvement (Slope of Growth): How steep is the student's growth trajectory compared to the growth rate required to close the achievement gap over time? (How fast is the student learning?)

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|                 THE DUAL-DISCREPANCY EVALUATION GRAPH                   |
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| Score                                                                   |
|   ^                                                                     |
|   |                                               [Grade Benchmark]    |
|   |                                          *    (Target Line)         |
|   |                                     *                               |
|   |                                *                                    |
|   |                           *                                         |
|   |                      *      o (Student A: Responsive - Closing Gap) |
|   |                 *      o                                            |
|   |            *      o                                                 |
|   |       *      o                                                      |
|   |  *      o                                                           |
|   |    o                                                                |
|   |                                                                     |
|   |  x-----------------------------------x (Student B: Unresponsive)    |
|   |  (Level is Low AND Slope is Flat)                                   |
|   +------------------------------------------------------------------>  |
|      Baseline   Wk 2   Wk 4   Wk 6   Wk 8   Wk 10   Wk 12     Time      |
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Mathematical Calculation of Growth Slope (Rate of Improvement)

To calculate a student's growth rate on Curriculum-Based Measurement probes (such as Words Correct Per Minute [WCPM] or Correct Letter Sounds [CLS]), teams determine the slope of the regression line across weekly or bi-weekly data points:

$\text{Rate of Improvement (Slope)} = \frac{\text{Final CBM Score} - \text{Baseline CBM Score}}{\text{Total Intervention Weeks}}$

For example, if a second-grade student begins Tier 2 intervention with a baseline score of 24 WCPM and reaches 40 WCPM after 8 weeks of intervention: $\text{Slope} = \frac{40 - 24}{8} = \frac{16}{8} = 2.0 \text{ WCPM per week}$

If typical grade-level peer growth is 1.2 WCPM per week, this student's growth slope of 2.0 WCPM/week is significantly steeper than peer growth. Even though the student's absolute performance level is still below grade-level benchmarks, their rate of improvement demonstrates that they are actively closing the gap. This student is responding positively to Tier 2!

The Four-Quadrant Decision Matrix

By cross-referencing Performance Level and Growth Slope, MTSS problem-solving teams make evidence-based placement decisions:

[!CAUTION] The Minimum Data Points Rule: A growth trend line cannot be established from 2 or 3 data points. Normal human variability, transient fatigue, or minor illness can distort isolated scores. To establish statistical validity, an MTSS team must collect a minimum of 6 to 8 data points over a sustained intervention period (typically 6 to 10 weeks) before calculating slope and making high-stakes tier-movement decisions.

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Realistic MTSS Problem-Solving Scenario

The Student Profile

Marcus is a second-grade student at a public elementary school in Gwinnett County, Georgia. On the Fall Universal Screening assessment (DIBELS 8th Edition Oral Reading Fluency [ORF]), Marcus achieved a score of 18 Words Correct Per Minute (WCPM) with 81% accuracy. The established beginning-of-year benchmark for second grade is 52 WCPM with 95% accuracy. Marcus ranks in the 4th percentile, placing him at substantial risk for reading failure.

Tier 2 Intervention Design & Execution

The school MTSS Student Support Team (SST) convenes and designs a targeted Tier 2 intervention:

• Diagnostic Target: Phonemic segmentation and closed-syllable phonics decoding.
• Intervention Program: An evidence-based, multisensory Structured Literacy supplemental program.
• Grouping: Group of 4 students with homogeneous phonics deficits.
• Dosage: 30 minutes daily, 4 days per week, scheduled during the school's 30-minute afternoon "Intervention & Enrichment" block (ensuring Marcus remains present for the entire 90-minute Tier 1 morning literacy block).
• Progress Monitoring: Administering an alternate-form second-grade ORF CBM probe every two weeks.

Progress Monitoring Data Collection (10 Weeks)

Over the 10-week intervention cycle, the reading interventionist meticulously logs attendance and collects 5 bi-weekly progress monitoring data points:

• Baseline: 18 WCPM
• Week 2: 19 WCPM
• Week 4: 21 WCPM
• Week 6: 20 WCPM
• Week 8: 22 WCPM
• Week 10: 23 WCPM

$\text{Marcus's Slope} = \frac{23 - 18}{10} = \frac{5}{10} = 0.5 \text{ WCPM per week}$

Team Problem-Solving Analysis

The SST team reconvenes to evaluate Marcus's data using the Dual-Discrepancy Model:

1. Fidelity Audit: The team inspects the interventionist's delivery logs and student attendance records. Marcus attended 38 out of 40 sessions (95% dosage adherence). The interventionist completed 100% of the scripted lesson routines. A peer-coaching observation on Week 5 verified high instructional quality. Fidelity is confirmed.
2. Performance Level Discrepancy: At Week 10, Marcus reads 23 WCPM. The second-grade winter benchmark is 72 WCPM. Marcus remains severely discrepant from grade-level expectations.
3. Rate of Improvement (Slope) Discrepancy: Marcus's growth rate is 0.5 WCPM/week. Expected peer growth for second graders is 1.3 WCPM/week, and closing the benchmark gap would require a growth slope of 2.5 WCPM/week. Marcus's growth slope is essentially flat, and the achievement gap between Marcus and his peers is actively widening.
4. Placement Determination: Marcus is a Dual Non-Responder under high-fidelity conditions. The team concludes that Tier 2 supplemental support is insufficient. Marcus is escalated to Tier 3 Intensive Intervention (1-on-1 instruction for 45 minutes daily using a specialized clinical Orton-Gillingham protocol). Concurrently, the team initiates a comprehensive multidisciplinary evaluation under IDEA to assess for a Specific Learning Disability in basic reading (Dyslexia).

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Common GACE Exam Traps & Misconceptions

[!WARNING] Trap 1: The Pull-Out Supplanting Trap. Exam questions frequently describe a scenario where a school schedules a struggling student's Tier 2 intervention during whole-class reading instruction to "double up" on literacy. This is illegal and pedagogically disastrous. Tier 2 and Tier 3 interventions must always be additive (supplemental), occurring outside the core literacy block.

[!WARNING] Trap 2: The Direct Special Education Referral Trap. A scenario presents a student who scores in the lowest 2nd percentile on a kindergarten or first-grade universal screener. The distractor states that the teacher should immediately refer the child for special education testing or place them on an IEP. In Georgia, students must move through MTSS tiers of evidence-based general education interventions first, documenting a dual discrepancy under validated fidelity, unless the parent formally requests an immediate evaluation in writing under IDEA procedural safeguards.

[!WARNING] Trap 3: Using Subjective Artifacts for Progress Monitoring. Candidates are often tempted by distractors suggesting that teachers should monitor Tier 2 progress using Friday spelling test scores, classroom journal entries, or end-of-unit basal comprehension tests. These informal tools lack reliability, standardized equivalence, and psychometric sensitivity. Progress monitoring in MTSS must be conducted using standardized, alternate-form Curriculum-Based Measurement (CBM) probes.

[!WARNING] Trap 4: Modifying Interventions Prematurely. When a student's CBM score drops on a single week (e.g., scoring 30 WCPM on Week 3 after scoring 34 on Week 2), distractors often advise changing the intervention curriculum immediately. The Science of Reading and psychometrics dictate that teams must never alter an intervention based on 1 or 2 erratic data points. A minimum of 6 to 8 data points is required to construct a valid trend line.