Does Common Core force me to teach that weird number line?

Yeah. That makes sense. Get that 1 a little closer to the 2.

In the past few days I've seen a few posts about the Common Core State Standards (CCSS) on Facebook, or other social media. The idea behind the posts is that the CCSS have forced teachers into teaching subtraction in a way that parents just don't understand. They claim that teachers are teaching kids to do this ridiculous number line. Kids have to convert the subtraction problem into an addition problem with an unknown variable, where kids count on from one addend to solve for the unknown variable.



So to solve the problem:

1000 - 123= x

Students would convert it to

123 + x = 1000

Sounds like Pre-Algebra.

Then they count on from 123.

123 + 7 = 130
130 + 70 = 200
200 + 800 = 1000

800 + 70 + 7 = 877

They show it in a number line, and it looks super confusing.

They also say a few of these gems.

1. This is what the CCSS is forcing our students to learn, and that teachers are no longer required to teach the standard algorithm. 
2. Someone is trying make them dumb, and trying to confuse parents
3. This is a new way of looking at math, why mess with something that isn't broken?

Here's my problem with that. None of this rhetoric is fact.

Let's take a look at what the actual CCSS says about what students should learn about Subtraction:

Fourth Grade; Number and Operations in Base Ten; Use place value understanding and properties of operation to perform multi-digit arithmetic

4. Fluently add and subtract multi-digit whole numbers using the standard algorithm. 

So... as a fourth grade teacher, I am required to be a). Familiar with the core, and b). get my kids to the point where they can add and subtract multi-digit whole numbers using the standard algorithm. The choice to teach using a number line to help kids get to the point where they are fluent with the conceptual idea of subtraction is a pedagogical decision left up to teachers. Some districts may encourage a style of teaching. Certain text books or curriculum may subscribe to different styles of teaching. The documents the Common Core was based on certainly encourage a conceptual understanding style of teaching. I have neither heard of nor experienced the idea that because I teach the Common Core, I should teach a certain way.

So is someone trying to make our students dumb, or trying to confuse parents? Believe this paranoia if you want. I know that I don't want a bunch of idiots running my city when I retire, so I'm working my tail off every year to make sure I send 35 kids into the world that can think for themselves.

But this is a new way of figuring out math though, right?

Hardly. Anytime I go to the store with my dad, he grumbles that nobody knows how to subtract these days. He always pays in cash. When the cashier gives him his change he gives them a lesson on how to give back correct change. It's incredibly embarrassing to be with the old guy that tries to give a math lesson at Home Depot, but it proves that this isn't a "new" way to look at subtraction. Let's look at our earlier example, but throw in a decimal, so it looks a little bit more like a real life scenario.

I buy something that costs $1.23. I pay with a $10.00 bill. The cashier hands me a wad of bills, and a handful of change. The cashier can quickly do the subtraction problem $10.00-$1.23=$8.77 without breaking a sweat.

Start with the pennies place...

$1.23 + $0.07 = $1.30

Then the dimes place...

$1.30 + $0.70 = $2.00

Then the one dollars place...

$2.00 + $8.00 = $10.00

The way the cashier should say it is, "$1.23 and $0.77 makes $2.00 and $8.00 makes $10.00.

This isn't new. My dad learned how to do a subtraction algorithm in his head like this in the 1960s while working at the Academy Theater. He didn't have a register or calculator, just had to do it in his head. So this isn't a new way of solving the problem invented by President Obama when he wrote the Common Core (sarcastic punctuation?). Many cashiers over the age of 50 count change out like this too. This isn't new.

So he could fluently add and subtract multi-digit numbers. Kinda like what I'm trying to get my kids to do.

So lay off the number line strategy. It is a solid way of looking at subtraction. It doesn't work with all of my students, but neither does the standard algorithm. The Common Core doesn't tell me how to teach. It just tells me what to teach. All the complaints I hear about the Common Core have nothing to do with the Common Core, they have more to do with the terrible curriculum teachers are using. ***THIS JUST IN*** Canned curriculum programs are terrible at writing math problems. Shocker of the century...



If you're going to criticize the Common Core, that's cool. But know what is in there before you do. Go read it, and turn down the volume. Because when we amplify everything, we hear nothing.