02-05-2015, 03:09 AM
The goal of common core is to teach number sense. Most kids have only known how to use a calculator. If they punch in the wrong numbers they get the wrong answer. Or, if they don't understand orders of operation the answer could be completely wrong. If they understand how to estimate in their head they'll know if the answer they get makes sense. The trick of breaking down the problem into smaller components is meant to help teach number sense.