Common Core
3.NBT.A.1
3 lessons teach this standard. Every lesson is interactive, and every one prints as a worksheet with a separate answer key.
Grade 3 Math · Chapter 2 · Lesson 1
Which ten is it closer to?
Grade 3 Math · Chapter 2 · Lesson 3
Estimating Sums and Differences
A quick answer that tells you if the real one is sensible.