1.3 Multi-Tiered System of Supports (MTSS) Decision Rules

Multi-Tiered System of Supports (MTSS) Decision Rules

A Multi-Tiered System of Supports (MTSS) is a comprehensive, schoolwide prevention framework that systematically coordinates academic instruction (Response to Intervention / RTI) and behavioral supports (Positive Behavioral Interventions and Supports / PBIS) into a seamless, data-driven continuum. The primary mission of MTSS is equitable prevention: providing high-quality core instruction to all students while allocating increasingly intensive, evidence-based interventions to students whose educational data demonstrate persistent academic or behavioral needs.

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The Three-Tiered Prevention Framework

                               ▲
                              ╱ ╲
                             ╱   ╲
                            ╱  T3 ╲    Tier 3: Intensive / Tertiary (1-5%)
                           ╱───────╲   • Highly individualized, 1:1 to 1:3 ratio
                          ╱         ╲  • 45-60 min daily; weekly progress monitoring
                         ╱   Tier 2  ╲
                        ╱─────────────╲ Tier 2: Targeted / Secondary (10-15%)
                       ╱               ╲• Small group (3-5 students), 30 min 3-4x/wk
                      ╱     Tier 1      ╲• Standard protocols; bi-weekly monitoring
                     ╱                   ╲
                    ╱─────────────────────╲ Tier 1: Universal / Core (80-85%)
                                            • High-quality evidence-based core curriculum
                                            • Differentiated instruction for all
                                            • Universal screening 3x/year

Comprehensive MTSS Tier Comparison

Praxis Key Concept: Tier 2 and Tier 3 supports are supplemental to Tier 1 core instruction, never a replacement. Pulling a struggling student out of core reading instruction to deliver a Tier 2 reading intervention violates MTSS architecture by depriving the student of the primary educational curriculum.

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Universal Screening & Diagnostic Accuracy

Universal screening is conducted three times per academic year (Fall, Winter, and Spring benchmark periods) to assess the health of core instruction and identify students in need of supplemental support.

The Psychometric Metrics of Screening

When evaluating the clinical validity of a universal screening battery, school psychologists evaluate four core psychometric metrics:

                               Actual Criterion Status
                              At-Risk          Not At-Risk
                         ┌───────────────┬───────────────────┐
          Flagged        │ True Positive │   False Positive  │
          At-Risk        │     (TP)      │        (FP)       │
Screener                 ├───────────────┼───────────────────┤
Outcome   Not Flagged    │ False Negative│   True Negative   │
          (Safe)         │     (FN)      │        (TN)       │
                         └───────────────┴───────────────────┘

1. Sensitivity (True Positive Rate): $$\text{Sensitivity} = \frac{TP}{TP + FN}$$ The probability that a student who will truly fail end-of-year benchmarks is correctly flagged as at-risk by the screener. High sensitivity minimizes False Negatives.
2. Specificity (True Negative Rate): $$\text{Specificity} = \frac{TN}{TN + FP}$$ The probability that a student who will successfully meet end-of-year benchmarks is correctly identified as not at-risk by the screener. High specificity minimizes False Positives.
3. Positive Predictive Value (PPV): $$\text{PPV} = \frac{TP}{TP + FP}$$ The proportion of students flagged as at-risk who actually fail the end-of-year criterion. Critical statistical fact: PPV is directly dependent on the base rate (prevalence) of the disorder in the school population. As prevalence decreases, PPV decreases dramatically, even if sensitivity and specificity remain high.
4. Negative Predictive Value (NPV): $$\text{NPV} = \frac{TN}{TN + FN}$$ The proportion of students classified as not at-risk who actually pass the end-of-year criterion.

The Educational Trade-Off: False Positives vs. False Negatives

• False Positive (Type I Screening Error): The screener flags a student as at-risk, but the student would have succeeded without intervention. Cost: Consumes intervention resources and teacher time, but the student receives extra academic support.
• False Negative (Type II Screening Error): The screener classifies a struggling student as safe, missing the need for support. Cost: Catastrophic. The student is denied early intervention during critical developmental windows and continues to fall further behind.

Praxis Rule of Thumb: Universal screening cut-scores are intentionally set to maximize sensitivity (typically ≥ .80–.90), accepting a higher rate of false positives to prevent false negatives. Cut-scores are typically anchored at the 20th to 25th percentile.

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Tier 2 Interventions: Standard Protocol vs. Problem-Solving Models

At Tier 2, schools deliver targeted interventions using one of two primary organizational models:

Quantifying Intervention Dosage

When designing or evaluating an intervention, the school psychologist must audit five dosage parameters:

1. Frequency: Number of sessions per week (e.g., 4 days/week).
2. Session Duration: Length of each session (e.g., 30 minutes).
3. Total Duration: Total weeks in the intervention cycle (typically 8 to 12 weeks).
4. Group Size: Teacher-to-student ratio (e.g., 1:4).
5. Active Responding Rate: Student opportunities to respond (OTR) per minute.

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Intervention Integrity & Treatment Fidelity Monitoring

Treatment integrity (or intervention fidelity) is the degree to which an intervention is implemented precisely as designed. In MTSS, treatment integrity is not an afterthought—it is the prerequisite for all data interpretation.

The Four Core Dimensions of Fidelity

1. Adherence (Procedural Integrity): Were all active ingredients and instructional steps implemented in the correct sequence without omissions?
2. Exposure / Dosage: Did the student receive the prescribed number of minutes and sessions? (Tracked via attendance logs).
3. Quality of Delivery: Did the interventionist deliver instruction with appropriate pacing, clear modeling, active engagement, and accurate error correction?
4. Student Responsiveness: Was the student actively attending, participating, and completing intervention activities?

Methods for Measuring Fidelity

• Direct Observation with Procedural Checklists (Gold Standard): An impartial observer (school psychologist or coach) directly observes a session, marking whether each prescribed step was executed ((Steps Implemented ÷ Total Steps) × 100). Conducted a minimum of 2–3 times per intervention cycle.
• Permanent Product Review: Examining completed student workbooks, audio recordings of sessions, or computerized session logs.
• Teacher Self-Report Checklists: Completed daily by the interventionist. Caution: Research consistently finds that self-reports overestimate fidelity compared with direct observation.

The 80% to 85% Fidelity Threshold Rule

Critical Praxis Rule: A team should not conclude that a student is an "intervention non-responder" from low CBM growth until treatment integrity has been checked. A common benchmark is ≥ 80% to 85%.

If a student shows flat progress and intervention fidelity is 55%, the student does not have a confirmed learning disability—the school has an implementation failure. The correct decision is to restore treatment fidelity, not refer to special education.

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Decision Gates & Special Education Referral under IDEA

Progressing through MTSS requires adhering to explicit data-based decision gates:

  [Universal Screening (Fall / Winter / Spring)]
                       │
         Score < 20th-25th Percentile?
            ├─── NO  ──► Maintain Tier 1 Core
            └─── YES ──► Initiate Tier 2 Standard Protocol (8-12 weeks)
                               │
                 Bi-Weekly Progress Monitoring & Fidelity Check
                               │
                 Adequate Rate of Improvement (ROI)?
                    ├─── YES ──► Fade to Tier 1 Core
                    └─── NO  ──► Check Integrity: Is Fidelity ≥ 80%?
                                    ├── NO  ──► Restore Integrity & Re-run
                                    └── YES ──► Intensify to Tier 3 (1:1 to 1:3)
                                                   │
                                     Weekly Progress Monitoring & Fidelity Check
                                                   │
                                     Persistent Dual Discrepancy After Tier 3?
                                        ├── NO  ──► Maintain/Step-Down Tier 2
                                        └── YES ──► Initiate IDEA Comprehensive
                                                    Special Education Evaluation

Decision Gate Thresholds

1. Gate 1: Tier 1 to Tier 2: Student scores below universal screening benchmark cut-score (typically < 20th–25th percentile) or meets a local decision rule such as a discrepancy ratio of about 1.5 or more, confirmed by a secondary diagnostic probe.
2. Gate 2: Tier 2 to Tier 3: Inadequate response after 1 to 2 cycles (8 to 16 weeks) of Tier 2 intervention delivered with verified fidelity (≥ 80%), characterized by flat slope and 4 consecutive points below aimline. Tier 3 intensifies dosage (45–60 min daily) and reduces group size (1:1 to 1:3).
3. Gate 3: Tier 3 to Comprehensive Evaluation (IDEA Referral): Persistent dual discrepancy (severe level deficit + flat growth slope) despite intensified Tier 3 intervention with documented high fidelity.

Child Find Mandates & Parental Rights under IDEA

A critical legal and ethical boundary frequently assessed on the Praxis is the intersection between MTSS and the Individuals with Disabilities Education Act (IDEA):

• Child Find Mandate (34 CFR § 300.111): School districts have an affirmative, ongoing legal obligation to identify, locate, and evaluate all children with suspected disabilities.
• No Delay or Denial (OSEP Memo 11-07): The federal Office of Special Education Programs (OSEP) issued explicit guidance establishing that an MTSS, RTI, or pre-referral process MAY NEVER BE USED TO DELAY OR DENY a timely comprehensive special education evaluation when a disability is suspected or when a parent submits a written evaluation request.
• Parental Request Protocol: If a parent requests an evaluation while the student is in Tier 2 or Tier 3:
  1. The district cannot say, "The student must finish our 12-week RTI cycle first."
  2. The district must either: (a) agree to evaluate, provide notice, and seek written parental consent; the 60-day timeline (or the state's own timeline) starts when consent is received, and interventions continue during the evaluation, or (b) provide PWN detailing why the district refuses to evaluate, grounded in existing data, and inform parents of due process rights.