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A Defense of (Some) Common Core Math

Posted by on March 31, 2014

Can someone explain how to solve this problem using a number line? (SOURCE: Facebook/Patriot Post)

OK, this isn’t really a defense of Common Core math – at least not all of it. It’s really just a defense of my interpretation of one particular homework problem. However, I believe there are implications for Common Core math in general.

Odds are good that you’ve already seen this image spreading virally on Facebook and elsewhere. In case you haven’t, you can read the Yahoo! Shine article on it. The tl;dr version is that the image is a scan or photo of a circuitous Common Core formula for obtaining the difference of 316 from 427 without simply calculating the subtraction. Instead of allowing his child to follow the assignment’s instruction to find the error “Jack” made, and explain the error in a letter to Jack, the father wrote a rant against Common Core mathematics approaches. He then posted the whole thing to a conservative Facebook page, Patriot Post.

It seems that agreeing with the frustrated father – that the “process used is ridiculous and would result in termination if used” by an electronics engineering such as him – has become a popular pastime among the parents I know. Without additional context, which I presume the child got in class, I must admit that I can’t figure out the right way to solve the problem. I’m not particularly gung-ho about Common Core, either. However, I don’t particularly care for knee-jerk criticisms. I also think too many parents are blinded by the prideful and obstinate certainty that the old ways they learned are superior.

More importantly, I think they’re afraid. Of what? Afraid of not being able to help their own children with their homework. Afraid that they’ll feel stupid or embarrassed because they could do their young child’s homework. Afraid that the world is changing around them, and they either can’t or don’t want to keep up.

Is this homework problem really that bad, though? While I’m known to be a bit old-fashioned and traditional in my values, I think this assignment, which has become a symbolic representation of Common Core standards, has been given a bad rap.Like I said, I don’t understand what method the assignment demands, but there’s something to be said for knowing multiple ways to arrive at the same answer. Government standards often infuriate me, but I actually look forward to learning this stuff with my kids. They’ll teach me the ways they know, and I’ll teach them the ways I know. 🙂

A method that may look convoluted when applied to a simple problem may be very quick and direct for a complex problem. However, such methods are learned in simple problems, not hard ones. Take, for instance, making change from cash payment by the method of “friendly numbers”.

To find the difference between two numbers, go from the lower number to a number that is a convenient multiple away from the higher number. For instance, adding 11 to 316 gets you to 327. From there, 427 is simply 100 away. 111, voila! You wouldn’t do long subtraction the old-fashioned way, with all the carries and whatnot, to make change, would you? So, if change can be made quickly and easily by another method, why not teach kids how to do that for any subtraction?

John Spencer, a blogger at Education Rethink had similar thoughts, pointing out that number lines help kids build “number sense”. Think of it as numeracy, the numerical analog to literacy. He also made these insightful remarks:

“Oddly enough, many of these same people who are mocking ‘new math’ in their posts are also lamenting the fact that Singapore is kicking our butts in math. What they fail to realize is that the places where math is working are the places where they are building number sense.

“I’ve seen what happens when students lack number sense. They learn a lockstep process and think that math is the same as baking a cake. They follow the recipe without understanding why they are doing what they are doing. However, when they get into something as simple as linear equations, they struggle to know what to “do first,” when there are often two or three options.

“When students lack number sense and they get the wrong answer, they fail to understand why an answer is illogical. You end up with a student who misplaces a decimal number and never finds his or her mistake. Asking students to think conceptually and engage in diagnostic problem-solving isn’t superfluous. It’s actually part of ‘the basics.'”


Oh, by the way, much fun as it can be to mock “New Math”, I’m pretty sure what Common Core teaches isn’t really New Math. I’ll leave figuring out the distinction as an exercise for the reader. 😉