Probe 1 Assessment IEP Probe 1
Missing Number Mastery
Equations up to 200 • Unknown in Any Position
Student:
Date:
Score: ___ / 6 (___ %)
Directions: Solve for the unknown in each equation. Show your strategy in the work space (count on, think addition, fact families, or base-ten sketch). Write your answer in the box.
#1
Addend Unknown
48 + ? = 115
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#2
Start Unknown
? − 37 = 86
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#3
Start Unknown
? + 59 = 143
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#4
Change Unknown
162 − ? = 75
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#5
Reversed Format
178 = ? + 94
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#6
Context Problem
Elena had 65 stickers. She bought a pack with more stickers. Now she has 150 stickers in all.
65 + ? = 150
Unknown =
Prompting Level: □ Independent (I) □ Verbal (V) □ Visual/Model (M)
Manipulatives Used: □ Yes □ No
Probe 2 Assessment IEP Probe 2
Missing Number Mastery
Equations up to 200 • Unknown in Any Position
Student:
Date:
Score: ___ / 6 (___ %)
Directions: Solve for the unknown in each equation. Show your strategy in the work space (count on, think addition, fact families, or base-ten sketch). Write your answer in the box.
#1
Addend Unknown
56 + ? = 124
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#2
Start Unknown
? − 49 = 78
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#3
Start Unknown
? + 68 = 155
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#4
Change Unknown
173 − ? = 86
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#5
Reversed Format
184 = 95 + ?
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#6
Context Problem
Leo had some crayons in a tin. He gave 42 crayons to his friend. Now he has 85 crayons left.
? − 42 = 85
Unknown =
Prompting Level: □ Independent (I) □ Verbal (V) □ Visual/Model (M)
Manipulatives Used: □ Yes □ No
Probe 3 Assessment IEP Probe 3
Missing Number Mastery
Equations up to 200 • Unknown in Any Position
Student:
Date:
Score: ___ / 6 (___ %)
Directions: Solve for the unknown in each equation. Show your strategy in the work space (count on, think addition, fact families, or base-ten sketch). Write your answer in the box.
#1
Addend Unknown
39 + ? = 118
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#2
Start Unknown
? − 54 = 67
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#3
Start Unknown
? + 76 = 162
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#4
Change Unknown
181 − ? = 95
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#5
Reversed Format
169 = ? + 88
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#6
Context Problem
A bakery baked 145 muffins. By noon, some were sold. There were 58 muffins remaining.
145 − ? = 58
Unknown =
Prompting Level: □ Independent (I) □ Verbal (V) □ Visual/Model (M)
Manipulatives Used: □ Yes □ No
Probe 4 Assessment IEP Probe 4
Missing Number Mastery
Equations up to 200 • Unknown in Any Position
Student:
Date:
Score: ___ / 6 (___ %)
Directions: Solve for the unknown in each equation. Show your strategy in the work space (count on, think addition, fact families, or base-ten sketch). Write your answer in the box.
#1
Addend Unknown
67 + ? = 135
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#2
Start Unknown
? − 46 = 89
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#3
Start Unknown
? + 84 = 171
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#4
Change Unknown
154 − ? = 68
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#5
Reversed Format
192 = 85 + ?
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#6
Context Problem
A sanctuary had some finches. 57 more finches arrived. Now there are 134 finches in all.
? + 57 = 134
Unknown =
Prompting Level: □ Independent (I) □ Verbal (V) □ Visual/Model (M)
Manipulatives Used: □ Yes □ No
Probe 5 Assessment IEP Probe 5
Missing Number Mastery
Equations up to 200 • Unknown in Any Position
Student:
Date:
Score: ___ / 6 (___ %)
Directions: Solve for the unknown in each equation. Show your strategy in the work space (count on, think addition, fact families, or base-ten sketch). Write your answer in the box.
#1
Addend Unknown
58 + ? = 127
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#2
Start Unknown
? − 65 = 79
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#3
Start Unknown
? + 49 = 136
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#4
Change Unknown
165 − ? = 78
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#5
Reversed Format
176 = ? + 98
Strategy used: □ Count On □ Think + □ Fact Family
Unknown =
#6
Context Problem
A puzzle has 180 total pieces. Maya has connected 93 pieces so far.
93 + ? = 180
Unknown =
Prompting Level: □ Independent (I) □ Verbal (V) □ Visual/Model (M)
Manipulatives Used: □ Yes □ No
Master Answer Key Teacher Key
Master Answer Key • Probes 1–3
Mastery Target: 5/6 (83%+)
Detailed strategy explanations, inverse relationships, and think-addition reasoning for IEP progress monitoring.
Probe 1 Key 6 Problems • Numbers up to 200
#1: 48 + 67 = 115
Strategy: Think-Add / Subtraction: 115 − 48 = 67. Count on from 48 (+2 to 50, +50 to 100, +15 to 115 → 2+50+15=67).
#2: 123 − 37 = 86
Strategy: Inverse Addition: 86 + 37 = 123. (Start is always the whole / total in subtraction).
#3: 84 + 59 = 143
Strategy: Subtract addend: 143 − 59 = 84. Think 143 − 60 = 83, add 1 back = 84.
#4: 162 − 87 = 75
Strategy: Count on from 75 to 162: 75 + 25 = 100; 100 + 62 = 162 → 25 + 62 = 87. Or 162 − 75 = 87.
#5: 178 = 84 + 94
Strategy: Inverse subtraction: 178 − 94 = 84. Equal sign indicates balance: total is 178.
#6: 65 + 85 = 150
Context: 150 − 65 = 85. Count on: 65 + 35 = 100, 100 + 50 = 150 → 35 + 50 = 85 stickers.
Probe 2 Key 6 Problems • Numbers up to 200
#1: 56 + 68 = 124
Strategy: 124 − 56 = 68. Think addition: 56 + 4 = 60, 60 + 64 = 124 → 4 + 64 = 68.
#2: 127 − 49 = 78
Strategy: Inverse Addition: 78 + 49 = 127. (78 + 50 = 128 − 1 = 127).
#3: 87 + 68 = 155
Strategy: 155 − 68 = 87. Decompose: 155 − 60 = 95, 95 − 8 = 87.
#4: 173 − 87 = 86
Strategy: 173 − 86 = 87. Count on: 86 + 14 = 100; 100 + 73 = 173 → 14 + 73 = 87.
#5: 184 = 95 + 89
Strategy: 184 − 95 = 89. Think: 95 + 5 = 100, 100 + 84 = 184 → 5 + 84 = 89.
#6: 127 − 42 = 85
Context: 85 + 42 = 127 crayons. Total is the starting amount in subtraction.
Probe 3 Key 6 Problems • Numbers up to 200
#1: 39 + 79 = 118
Strategy: 118 − 39 = 79. Count on from 39: +1 → 40, +60 → 100, +18 → 118 = 79.
#2: 121 − 54 = 67
Strategy: Inverse Addition: 67 + 54 = 121. (67 + 50 = 117, + 4 = 121).
#3: 86 + 76 = 162
Strategy: 162 − 76 = 86. Think: 162 − 70 = 92, 92 − 6 = 86.
#4: 181 − 86 = 95
Strategy: 181 − 95 = 86. Count on: 95 + 5 = 100, 100 + 81 = 181 → 5 + 81 = 86.
#5: 169 = 81 + 88
Strategy: 169 − 88 = 81. Think: 169 − 89 = 80, so 169 − 88 = 81.
#6: 145 − 87 = 58
Context: 145 − 58 = 87 muffins. Count on: 58 + 2 = 60, + 40 = 100, + 45 = 145 → 87.
Page 1 of 2 Probes 4–5 & Diagnostic Analysis on Page 2 →
Teacher Key
Master Answer Key • Probes 4–5 & Error Analysis
Diagnostic Rubric
Probe 4 Key 6 Problems • Numbers up to 200
#1: 67 + 68 = 135
Strategy: 135 − 67 = 68. Think near-doubles: 67 + 67 = 134, so 67 + 68 = 135.
#2: 135 − 46 = 89
Strategy: Inverse Addition: 89 + 46 = 135. (89 + 1 = 90, 90 + 45 = 135).
#3: 87 + 84 = 171
Strategy: 171 − 84 = 87. Count on: 84 + 16 = 100, 100 + 71 = 171 → 16 + 71 = 87.
#4: 154 − 86 = 68
Strategy: 154 − 68 = 86. Think: 68 + 32 = 100, 100 + 54 = 154 → 32 + 54 = 86.
#5: 192 = 85 + 107
Strategy: 192 − 85 = 107. Count on: 85 + 15 = 100, 100 + 92 = 192 → 15 + 92 = 107.
#6: 77 + 57 = 134
Context: 134 − 57 = 77 finches. (134 − 54 = 80, 80 − 3 = 77).
Probe 5 Key 6 Problems • Numbers up to 200
#1: 58 + 69 = 127
Strategy: 127 − 58 = 69. Think: 58 + 2 = 60, 60 + 67 = 127 → 2 + 67 = 69.
#2: 144 − 65 = 79
Strategy: Inverse Addition: 79 + 65 = 144. (80 + 64 = 144).
#3: 87 + 49 = 136
Strategy: 136 − 49 = 87. Think: 136 − 50 = 86, add 1 = 87.
#4: 165 − 87 = 78
Strategy: 165 − 78 = 87. Count on: 78 + 22 = 100, 100 + 65 = 165 → 22 + 65 = 87.
#5: 176 = 78 + 98
Strategy: 176 − 98 = 78. Think: 176 − 100 = 76, add 2 = 78.
#6: 93 + 87 = 180
Context: 180 − 93 = 87 puzzle pieces. (93 + 7 = 100, 100 + 80 = 180 → 87).
Diagnostic Error Analysis Guide for IEP Progress Monitoring
Operation Reversal Error
Error: Student subtracts when start is missing (e.g., in ? − 37 = 86, calculates 86 − 37 = 49).
→ Intervention: Teach "Part-Part-Whole" diagram. Emphasize that the first number in subtraction is the whole (total).
Reversed Format Misconception
Error: In 178 = ? + 94, student adds 178 + 94 = 272 treating '=' as 'perform operation'.
→ Intervention: Use pan balance scales. Teach '=' as a balance point ("the same amount on both sides").
Regrouping Over 100 Deficit
Error: Computational slips crossing 100 on open number lines (e.g. from 80 jumps incorrectly to 100).
→ Intervention: Explicitly teach "friendly landmark jumps" to 100 using base-ten rods or an open number line.
IEP Mastery Decision: 80%+ accuracy (5/6 correct) across 3 consecutive probes administered under independent conditions.
Page 2 of 2
Goal Progress Tracker IEP Documentation
IEP Goal Data & Progress Tracker
Teacher Data Sheet
Student Name:
Case Manager:
Target Date:
IEP Goal: Given an addition or subtraction equation of three whole numbers up to 200 with one unknown in any position (e.g., 18 + __ = 54, __ - 9 = 26), student will solve for the unknown number by using an addition or subtraction strategy (e.g., count on, "think addition" to solve subtraction, fact families, using manipulatives) with 80%+ accuracy across 3 consecutive probes.
Probe
Date
Score
% Acc.
Dominant Strategy
Prompt
Met ≥80%?
Teacher Notes / Error Pattern
Base
/ 6
%
I / V / M
Y / N
Baseline administration
P-1
/ 6
%
I / V / M
Y / N
P-2
/ 6
%
I / V / M
Y / N
P-3
/ 6
%
I / V / M
Y / N
P-4
/ 6
%
I / V / M
Y / N
P-5
/ 6
%
I / V / M
Y / N
Strategy Codes:
CO: Count On (Line) TA: Think Addition FF: Fact Family / Inverse BT: Base-Ten / Blocks
Prompting Level Codes:
IND (I): Independent (0 prompts) VP (V): Verbal Prompt / Cue GP (G): Gestural / Visual Point MOD (M): Teacher Modeling
Instructional Adaptation Protocol:
Progress Positive: If score is ≥ 83% (5/6) for 3 consecutive probes under Independent conditions, goal is mastered. Transition to numbers within 1,000.Flat Line / Stagnation: If score remains between 50%–67% across 2 probes, evaluate strategy efficiency; provide targeted small-group instruction on Think Addition.Regression / Low Score: If score is < 50% on 2 consecutive probes, reintroduce concrete base-ten manipulatives and review part-part-whole relationships.
Confidential Special Education Document Student Visual Tracker on Page 2 →
My Progress
Equation Detective Progress Graph
Mission Target: 5 or 6 Stars!
Detective Name:
Color your score bar after each probe!
Score Tracker (Number of Correct Equations) Goal Line: 5+ Correct (83%)
Mastery Target (5/6)
6 (100%) 5 (83%) 4 (67%) 3 (50%) 2 (33%) 1 (17%) 0
Base
Probe 1
Probe 2
Probe 3
Probe 4
Probe 5
Detective Strategy Tool Belt (Color the strategies you mastered!)
🚶
Count On
Jump on the line
🤔
Think Addition
Add to subtract
🔗
Fact Family
Part + Part = Whole
🧱
Base-Ten
Sketch tens & ones
My Goal Reflection:
My favorite strategy to find the missing number is:
When an equation has a missing number in the front, I remember to:
Every probe helps me grow stronger in math! Keep this in your math folder
