Explain My Child's Mistake
Don't just mark an answer right or wrong. Our Error Pattern Engine analyzes the exact cognitive misconception behind the mistake and automatically generates a 4-step scaffolded visual remediation sheet.
2-Digit Subtraction with Regrouping
Sample: 52 - 27 = 35
Multi-Digit Addition Carrying Drop
Sample: 48 + 37 = 715
Adding Like Fractions (Denominator Addition Trap)
Sample: 1/4 + 2/4 = 3/8
Multiplication by Zero Confusion
Sample: 8 × 0 = 8
Pattern: Smaller-From-Larger Digits Trap (No-Borrowing Reversal)
2-Digit Subtraction with Regrouping
Level: Grade 2 / Year 2
🔍 Pedagogical Diagnosis:
The child observed the ones column (2 and 7). Instead of recognizing that 2 is smaller than 7 and borrowing a ten from 50, they reflexively subtracted 7 - 2 = 5. In the tens column, they did 5 - 2 = 3, yielding 35 instead of 25.
💡 Step 1: Visual Conceptual Breakdown
Think of 52 as 5 TENS and 2 ONES. You cannot take 7 ones away from 2 loose ones. So we UNBUNDLE 1 ten: 52 becomes 4 TENS and 12 ONES! Now: 12 ones - 7 ones = 5 ones. 4 tens - 2 tens = 2 tens. Result: 25!
🔍 Step 2: Guided Mirror Examples with Thinking Hints
43 - 18
Hint: 3 is smaller than 8. Regroup 43 into 3 tens and 13 ones! 13 - 8 = 5, 3 - 1 = 2.
Answer: 25
61 - 25
Hint: 1 is smaller than 5. Regroup 61 into 5 tens and 11 ones! 11 - 5 = 6, 5 - 2 = 3.
Answer: 36✍️ Step 3: Scaffolded Practice with Prompt Fading
34 - 17
(Regroup to 2 tens and 14 ones → 14 - 7 = ? ; 2 - 1 = ?)
72 - 38
(Regroup to 6 tens and 12 ones → 12 - 8 = ? ; 6 - 3 = ?)
55 - 29
(Regroup to 4 tens and 15 ones → 15 - 9 = ? ; 4 - 2 = ?)
🏆 Step 4: 5 Independent Mastery Challenge Questions
Have the child solve these completely on paper without assistance:
Challenge 1
41 - 16 = ?
Challenge 2
63 - 27 = ?
Challenge 3
82 - 45 = ?
Challenge 4
54 - 38 = ?
Challenge 5
90 - 34 = ?