1.2 Curriculum-Based Measurement & Progress Monitoring

Curriculum-Based Measurement & Progress Monitoring

Curriculum-Based Measurement (CBM), originally developed by Stanley Deno and colleagues at the University of Minnesota Institute for Research on Learning Disabilities in the late 1970s and 1980s, is the gold-standard formative assessment framework in school psychology. CBM replaced subjective teacher ratings and infrequent standardized achievement testing with an objective, frequent, and psychometrically robust measurement system designed to gauge student responsiveness to instructional interventions.

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CBM Principles & Psychometric Foundations

CBM is distinguished by several non-negotiable measurement principles:

1. Brief and Repeatable: Probes require only 1 to 3 minutes to administer (math computation up to 8 minutes), minimizing intrusion into instructional time while allowing weekly or bi-weekly administration.
2. Standardized Administration and Scoring: Administration uses verbatim script directions, rigid timing protocols (stopwatch required), and explicit objective scoring rubrics, yielding high inter-rater agreement (r > .90).
3. Multiple Equivalent Alternate Forms: Each probe within a grade-level pool is designed to be of equivalent psychometric difficulty, ensuring that changes in score reflect actual student skill acquisition rather than passage variability.
4. Sensitive to Small Increments of Growth: Unlike broad norm-referenced achievement tests (which require 6–12 months to detect measurable change), CBM detects weekly micro-increments of learning.
5. Formative Assessment Utility: CBM is fundamentally formative—used dynamically during instruction to modify teaching practices before summative failure occurs.

General Outcome Measurement (GOM) vs. Mastery Measurement (SMM)

Understanding the distinction between General Outcome Measurement (GOM) and Subskill Mastery Measurement (SMM) is a frequent topic on the Praxis School Psychologist exam.

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Standardized CBM Probes Across Domains

                                  CBM Battery
        ┌──────────────────────────────┼──────────────────────────────┐
        ▼                              ▼                              ▼
  Early Literacy & Reading        Mathematics                Written Expression
  • FSF (Initial sounds)         • M-COMP (Computation:      • TWW (Total Words Written)
  • PSF (Phoneme segments)         Correct Digits)           • WSC (Words Spelled Correctly)
  • NWF (Nonsense words:         • M-CAP (Concepts &         • CWS (Correct Writing Sequences)
    CLS & WWR)                     Applications)
  • ORF / DORF (WCPM)
  • Maze (Silent comprehension)

1. Early Literacy Probes (DIBELS / Acadience Reading)

• First Sound Fluency (FSF): Standardized 1-minute oral probe assessing phonemic awareness in Kindergarten. Examiner says a word (e.g., "cat"), student says the first sound (/k/ = 2 points; /ka/ = 1 point). Target benchmark: 30+ by middle of kindergarten.
• Phoneme Segmentation Fluency (PSF): 1-minute oral probe (Kindergarten–Grade 1). Examiner says a word (e.g., "stop"); student segments into individual phonemes (/s/ /t/ /o/ /p/ = 4 points). Target benchmark: 40+ phonemes/minute by end of kindergarten.
• Nonsense Word Fluency (NWF): 1-minute probe (Grade K–Grade 2) assessing the alphabetic principle and phonological recoding. Standard consonant-vowel-consonant (CVC) pseudowords (e.g., lat, sig, vop). Scored on two metrics: Correct Letter Sounds (CLS) and Whole Words Read (WWR) without hesitation.

2. Oral Reading Fluency (ORF / DORF)

• Administration: 1-minute timed reading of an unpracticed, standardized grade-level passage.
• Metric: Words Correct Per Minute (WCPM) = Total Words Read minus Errors.
• Exact Standard Scoring Rules:
  • Counted as Errors: Mispronunciations, word substitutions, word omissions, transpositions, and hesitations exceeding 3 seconds (examiner provides the word and marks an error).
  • NOT Counted as Errors: Self-corrections within 3 seconds, repetitions, insertions, and accent/dialectical variations.

3. Maze Comprehension

• Administration: 3-minute silent reading probe (typically Grades 3–8).
• Structure: The first sentence is unaltered. Beginning in the second sentence, every 7th word is deleted and replaced with a 3-choice multiple-choice option: (1) the correct word, (2) a distractor of the same part of speech, and (3) an unrelated syntactically incongruent distractor.
• Scoring: Total correct selections minus half errors (to adjust for guessing: C − E/2), or raw correct restorations within 3 minutes.

4. Mathematics Computation (M-COMP)

• Administration: Standardized timed worksheet (2 to 8 minutes depending on grade).
• Scoring by Correct Digits (CD): Rather than scoring answers solely as binary right/wrong, credit is awarded for each correct digit in the mathematical calculation (including intermediate digits in multi-digit multiplication and long division). Scored from right to left for addition/subtraction/multiplication. Clinical Advantage: Correct Digits provide vastly greater sensitivity to incremental learning and reward partial algorithmic mastery.

5. Mathematics Concepts and Applications (M-CAP)

• Administration: 8- to 10-minute standardized probe evaluating applied mathematical reasoning, word problem solving, measurement, time, money, and graphical interpretation.

6. Written Expression (WE-CBM / CBM-W)

• Administration: Student is given a standardized story starter prompt (e.g., "I stepped outside and was shocked to see..."), allowed 1 minute to think and plan, and exactly 3 minutes to write continuously.
• Three Primary Metrics:
  1. Total Words Written (TWW): Total count of words generated regardless of spelling or syntax (Fluency/Volume indicator).
  2. Words Spelled Correctly (WSC): Count of words spelled correctly in isolation (Orthographic accuracy indicator).
  3. Correct Writing Sequences (CWS): The gold standard metric for syntactic, semantic, and grammatical competence.

The Correct Writing Sequence (CWS) Scoring Rules

A Correct Writing Sequence (CWS) is defined as two adjacent, correctly spelled words that are grammatically, syntactically, and semantically acceptable within the context of standard English, including capitalization and punctuation.

• A caret symbol (^) is placed above each valid sequence pair:
  • The space before the first word requires correct capitalization (^ Word).
  • Two adjacent words must be spelled correctly and make grammatical sense (Word1 ^ Word2).
  • The space before terminal punctuation requires grammatically acceptable ending punctuation (Word ^ .).
  • The space after terminal punctuation requires a capital letter to begin the next sentence (. ^ Word).

Example Scoring Analysis:
Text written: "The dog runned fast. He barked"
CWS Carets:    ^ The ^ dog [runned] fast ^ . ^ He ^ barked
Breakdown:
  1. [^ The]      = Valid (capitalization)
  2. [The ^ dog]   = Valid (grammar & spelling)
  3. [dog - runned]= INVALID ("runned" is misspelled/incorrect grammar)
  4. [runned - fast]= INVALID (adjacent to an error)
  5. [fast ^ .]    = Valid (punctuation)
  6. [. ^ He]      = Valid (post-punctuation capitalization)
  7. [He ^ barked] = Valid (grammar & spelling)
Total TWW = 6 words | Total CWS = 5 sequences

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Establishing Baseline, Aimlines, & Trendlines

1. Establishing the Baseline: The Median Rule

• Administer three alternate-form probes of equivalent grade-level difficulty across separate testing sessions (or consecutively with short rest intervals).
• The Rule of the Median: Arrange the three scores in numerical order and select the median score (the middle score).
  • Example Probes: 42 WCPM, 38 WCPM, 55 WCPM. Median = 42 WCPM.
  • Why not the mean? The median prevents an anomalous single-session outlier (such as the 55 WCPM score caused by accidental passage familiarity) from skewing the baseline. If an even number of probes (e.g., 2) were administered, take the lower of the two scores or administer a third.

2. Constructing the Aimline

The aimline (goal line) represents the expected trajectory of student growth from baseline to the target horizon.

$$\text{Target Aimline Score} = \text{Baseline Median} + (\text{Target Weekly Slope} \times \text{Instructional Weeks})$$

Fuchs et al. (1993) Weekly ORF Growth Rates (WCPM per Week)

These classic rates (Fuchs, Fuchs, Hamlett, Walz, & Germann, 1993) are a starting point. Many teams now use the growth norms published with their own screening tool, or local norms.

3. Calculating Trendlines

Progress data are collected weekly or bi-weekly under identical standardized conditions. To evaluate progress, a trendline (line of actual progress) is calculated:

• Ordinary Least Squares (OLS) Linear Regression: The mathematical gold standard (y = mx + b). Modern CBM software automatically calculates the OLS slope (b).
• Split-Middle / Tukey Method (Quarter-Intersect Method): A standardized hand-graphing technique where progress data are divided into two equal vertical halves, medians are identified for each half, a line is drawn connecting the intersection points, and the line is shifted parallel so that 50% of all data points fall above and 50% fall below the line.

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Formative Decision Rules: The 4-Point Rule

School psychologists do not wait until the end of a semester to evaluate intervention efficacy. Standard CBM formative decision rules guide continuous adjustment:

                                Progress Data Plotted
                                          │
               ┌──────────────────────────┼──────────────────────────┐
               ▼                          ▼                          ▼
      4 Consecutive Points       4 Consecutive Points      Points Oscillate
         BELOW Aimline              ABOVE Aimline           Around Aimline
               │                          │                          │
               ▼                          ▼                          ▼
     [MODIFY INTERVENTION]         [RAISE AIMLINE]         [MAINTAIN PLAN]
     • Increase dosage             • Increase target       • Continue current
     • Reduce group size             growth rate             instructional plan
     • Change teaching strategy    • Or plan for fading      with high fidelity

1. The 4-Point Rule (Below Aimline): If four consecutive data points fall below the aimline, the intervention is deemed ineffective. The school psychologist and team must convene immediately to modify the instructional plan (increase dosage, reduce group size, change pedagogy).
2. The 4-Point Rule (Above Aimline): If four consecutive data points fall above the aimline, the student's rate of progress exceeds initial expectations. The team should raise the aimline goal to maintain high expectations, or begin planning for fading toward general core instruction.
3. Hovering Around Aimline: If data points oscillate evenly around the aimline, maintain the intervention without alteration.
4. Slope Comparison Rule: After 6 to 8 weeks of data collection, calculate the slope of the empirical trendline (b). If b < aimline slope, an instructional change is warranted even if points have not yet triggered the strict 4-point rule.

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The Dual Discrepancy Model for SLD Identification

Under IDEA 2004 regulations, local educational agencies are permitted to use a process based on the child's response to scientific, research-based intervention (RTI) to determine Specific Learning Disability (SLD). The dual discrepancy model (pioneered by Lynn and Douglas Fuchs) provides the empirical foundation for this determination.

To be identified with a Specific Learning Disability under the dual discrepancy model, a student must simultaneously demonstrate two independent discrepancies:

                          The Dual Discrepancy Matrix

                      Performance Level Discrepancy?
                          YES                     NO
                 ┌──────────────────────┬──────────────────────┐
             YES │     QUADRANT D       │     QUADRANT C       │
Rate of          │  **DUAL DISCREPANT** │   Unusual Profile:   │
Improvement      │   • Specific Learning│   • High baseline,   │
(ROI)            │     Disability (SLD) │     declining slope  │
Discrepancy?     ├──────────────────────┼──────────────────────┤
             NO  │     QUADRANT B       │     QUADRANT A       │
                 │   "Slow Starter":    │   Normal / Typical   │
                 │   • Low level, but   │   • Benchmark level, │
                 │     steep slope      │     adequate slope   │
                 │   • NOT DISABLED     │   • NOT DISABLED     │
                 └──────────────────────┴──────────────────────┘

1. Discrepancy 1: Level Deficit (Current Performance): The student's absolute level of achievement is substantially below that of age- or grade-level peers (typically below the 10th to 16th national percentile, or demonstrating a Discrepancy Ratio ≥ 1.5–2.0).
2. Discrepancy 2: Rate of Improvement (ROI) Deficit (Learning Slope): Despite the provision of an evidence-based, scientifically validated intervention delivered with high fidelity, the student's weekly rate of improvement (trendline slope) is significantly flatter than that of normative peers.

Exam Trap Alert: A student who exhibits a low performance level but demonstrates an average or steep growth slope when given Tier 2 intervention is NOT dual discrepant. This student is a "responder" whose deficit stemmed from experiential lack or poor prior instruction, not an intrinsic learning disability.