The New Way of Subtracting – Crushing a Facebook Meme

“Oh – I see what they’re doing,” I thought to myself after spending 20 seconds looking at the latest bash-the-common-core meme:

The “new way” is really the old fashioned way of giving change, before we had cash registers with computers in them.

Getting change, the old fashioned way.

I buy something and it costs \$12. So I give you \$32. (Because I’m a freak OR I anticipate not having so many \$1’s in my pocket after this is over.)

Your fancy-schmancy cash register computer is out (or doesn’t exist), so you need to give me change out of your head.

Now theoretically (or in reality) you’d recognize what I was doing and say, “Gee, you want a \$20 bill back,” and you’d hand it to me.

But let’s suppose you didn’t recognize that.

Here’s how you’d do it:

You say, “Your total was 12 and there’s…”

While giving me three \$1 bills, you say, “…13, 14, 15…”

Then you give me a five dollar bill and say, “…20…”

Then you give me a ten dollar bill and say, “…30…”

Then you finish off with handing me two ones and saying, “… 31 and 32.”

Granted, I’d have lots of ones and be annoyed with you. But you would have certainly given me all \$20 that I was due.

So why all the fuss?

Many people, including me, have written about how the common core isn’t a curriculum. It’s a set of guidelines to help teachers help students think about math.

Nobody says (or should say) that you must do subtraction this way. Instead it’s suggested that there’s more than one way to look at subtraction.

What do you think about the way people are freaking out about the common core state standards? How are you handling it?

Share your thoughts in the comments or tweet it out. And don’t forget to post on Pinterest too!

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