Mathematics
Addition & Subtraction
Meta
7–9 yrs
Estimating by rounding
四舍五入估算
Description
Estimate the answer to a calculation and use inverse operations to check answers; apply to increasingly large numbers using rounding and inverse reasoning
Mastery Evidence
- Round numbers to the nearest 10 or 100 to estimate a sum or difference before calculating
- Use addition to check a subtraction answer, or vice versa
- Identify when a calculated answer is unreasonable based on the estimate
- Round numbers to estimate a sum or difference before calculating
- Use addition to check a subtraction answer and vice versa
- Identify an unreasonable answer by comparing to the estimate
Assessment Prompt
Before your child works out a calculation, can they make a sensible rough guess — and then check their answer using the opposite operation?
