Mathematics · Grades 2–5
Find the mistake: number sense · revision card
A correction is stronger when it names the mistaken rule or place value.
Keep these ideas clear
Explain the step
A correction is stronger when it names the mistaken rule or place value.
Estimate first
An estimate can reveal an unreasonable result before detailed checking.
Two useful examples
A pupil says 48 + 27 = 615 because 4 + 2 = 6 and 8 + 7 = 15. Correct the answer and explain.
48 + 27 = 75. Regroup 15 ones as 1 ten and 5 ones; 4 + 2 + 1 = 7 tens.
48 + 27 = 75. Regroup 15 ones as 1 ten and 5 ones; 4 + 2 + 1 = 7 tens.
A pupil says 302 − 198 = 196. Use a nearby-number strategy to correct it.
302 − 200 + 2 = 104. Subtracting 200 removes two too many, so add two back.
302 − 200 + 2 = 104. Subtracting 200 removes two too many, so add two back.
Explain it without looking
- Explain why 9 × 7 = 10 × 7 − 7.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.