Dear "Frustrated Father": Stop acting like an idiot.

The Internet is all atwitter this week about a "Frustrated Parent" (Jeff Severt, by name) who couldn't figure out "his son's Common Core math assignment" (I put that in quotation marks, because that's what a journalist wrote, and journalists are not always accurate in their reporting. (Imagine that!)).

The father's version of the homework first appeared on a conservative Facebook page called The Patriot Post. It was picked up by TheBlaze, who published a breathless article about it. That article caught Glen Beck's eye, and he did an interview with the father. From there, it went viral. For example, Yahoo has been hooting about it for days.

So what was the homework assignment? Here's the photo that was posted on Facebook. (FB lawyers: I claim "fair use." Get away from me.)

There are a number of things that are just plain wrong with Mr. Severt's response. I don't know where to start. Let's start at the beginning.

1. He didn't read the instructions. The problem says, "Write a letter to Jack, telling him what he did right, and how to fix his mistake." Mr. Severt responds that 427 minus 316 is obviously 111, and that he could figure it out in under five seconds. Well, that's great, Jeffy, but that's not what the teacher was asking for. The fictional kid got 121 for his answer. What did he do right, and more importantly, what did he do wrong and how should he fix it? An engineer should be able to figure that out. (I'll tell you below.)

2. Mr. Severt, who is so proud of his Bachelor of Science Degree in Electrical Engineering, who can do differential equations, and who (I assume) can read both an electrical schematic and an oscilloscope waveform, is unable to figure out a simple number line. I glanced at the diagram and figured out the problem almost instantly - in less than a second, anyway. (Wanna know the answer? Keep reading.)

For your information, Mr. Severt, we lose a lot of kids in K-12 when we try to teach them to do subtraction via the vertical method. Many students, like you and me, did just fine learning math that way. But a significant number of students are visual learners, some are kinesthetic learners, and some have dyslexia. For these students, it really, really, REALLY helps for them to use a number line to figure out the mechanics of subtraction. We teach them how to add and subtract on a number line, and then we show them how the number-line method corresponds to the vertical method. Eventually they have an "a-hah!" moment where it all makes sense, and then they can leave the number line behind.

It's like training wheels on a bicycle.

Or do you want an example from your Electrical Engineering curriculum? Let's talk about calculus. Do you remember L'Hôpital's Rule? Limits? Do you use those in your EE job? Well, you do calculus, right? When's the last time you actually had to use L'Hôpital's Rule? You spent a whole unit on it in Calc 1. It was on the midterm and on the final. Learning and understanding L'Hôpital's Rule was fundamental to understanding differentiation, and integration after that. That is analogous to teaching subtraction on the number line.

Five years before Common Core came about, I was teaching my seventh grade math students how to add and subtract positive and negative numbers, using a number line. It works.

3. "In the real world, simplification is valued over complication." Mr. Severt, I dare you to try to teach a second-grader about three-digit vertical subtraction, your way. Your explanation will be much more complicated, and less understandable by the majority of your students, than the number line.

4. About the number line, Mr. Severt says "The process is ridiculous and would result in termination if used." This is both arrogant and disingenuous. You know what? It's also a stupid thing to say. As I have shown above, the number line is a K-12 teaching tool, not a professional-level algorithm.

5. I will assert, with no data to back me up, that most of the anti-Common Core crowd are just repeating claims they've heard (like the silly "It's okay to say 3 x 4 = 11" claim) and anecdotes like this "Frustrated Father" one, and that none of these parrots have actually read the Common Core standards. If you think I'm talking about you, then, Dear Reader, you're probably right. GO READ THEM FROM THE SOURCE. What you are arguing against is not Common Core.

I think that this point, the point about learning about CC from the source, deserves another blog entry. Read it here.

6. For those of you still reading this, here's the answer. It takes longer to explain it than it does to comprehend it. To solve 427-316 on a number line, you start at 427. Take three 100-sized jumps to the left, one 10-sized jump to the left, and six single jumps to the left. You will end up at 111. The fictional Jack forgot the 10-sized jump and that's how he ended up at 121.

You're welcome.

(UPDATE! The Huffington Post published about this, two days after I did. Read their article here, and my observations about it here.)

(ANOTHER UPDATE! Seven months later, the Independent Journal Review has picked up on this, and published an article about it as if it were brand new. Seven months! Clearly, they're a little slow on the uptake. They also have problems reading for comprehension. Read their article here, and my further thoughts on the matter here. Too many people have forgotten the "slow" kids in their grade-school math classes.)