Monday

"New" Math of the Common Core is really THOUGHT Math

Circulating around the internet is a basic subtractions problem and an alternative way (under the Common Core curriculum) about how a student might go about finding the solution.


32 - 12 = ___

Here's an intuitive but not traditional way of solving it (although it does use the method of "adding to subtract" -- a way that first grade teachers have been using all over for years):  

- From "12" count up to the next number with a base of 5...   or "15"
- From "15" count up to the next number with a base of 10 ... or "20".  Generally, bases of 10 make for easy math.
- From the base of 10, count to the closest number with a base of 10 and careful not to exceed the integer ...  here, we count to "30" the closest base-10 integer without going over "32."
- Add any additional ones that it takes to reach the integer ... or "2" more ones.

Essentially, 
we have added "12" plus "3" more to make "15"
then we have added "15" plus "5" more to make "20"
then we have added "20" plus "10" more to make "30"
finally we have added "30" plus "2" more to make "32"

If we account for everything we had to "add" to get from "12" to "32"... we reach the answer of "20" (3+5+10+12).  

Although this sounds complicated, it's actually mental math that many people do everyday.  Here's a great article that explains why this method is really not "new" and probably doesn't deserve visceral reactions

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