Grade Level: 3rd Skill: Reasoning Topic: Estimate to See if an Answer Works Goal: Use estimation to verify the reasonableness of calculated results. Skill Description: Mathematical Reasoning: estimation, reasonableness, problem solving The ability to use a reasonable guess to figure out mathematical problems and the ability to know when it’s appropriate to use a guess and when it’s appropriate to use a precise calculation.

## Building Blocks/Prerequisites

### Sample Problems

 (1) Is estimation reasonable? Myles is practicing for a 100 -yard dash. He wants to know how much greater his trial time is than the race record time of 9.4 seconds.(Myles needs to know exactly how much faster he needs to go to beat the record, so estimation is not a good strategy.) (2) Is estimation reasonable? Sheri is on duty as a lifeguard. It is 11:39 am. She wants to stop by the market on the way home. At what time shall she tell his friends she will arrive at the market? (Sheri does not need to arrive at the market at an exact time, so she can estimate the time.) (3) Estimate: 71 + 38 + 56 + 10 + 43 + 37 + 22 = ? (4) Use front-end estimation to add 53 + 98. (50 + 90= 140) (5) Use rounding to estimate 569 + 453. (570 + 450 = 1020)

### Online Resources

 (1) (2) (3) (4) (5)