#CommonCoreSubtractionOnANumberLineIsJustPlainStupid

As my title might suggest, I've recently become fed up with a new system of teaching math (specifically subtraction) under the Common Core system. Since my kids have joined the public school system this year, I've slowly gotten bits a pieces of the overall curriculum through their studies and have been frustrated more than once. This particular rant isn't about anything they brought home, but rather something I read online.

I read an article today on The Blaze that was a mildly humorous post that a supposed frustrated parent wrote on their child's math homework. Feel free to check it out here. In a nutshell, the homework page asks a seemingly simple math problem concerning the difference between two 3-digit numbers. Simple right? Oh, how wrong you are. You see, we (that is, everyone over the age of 8 today) obviously learned subtraction incorrectly. Line up the digits and commence with single digit subtraction, complete with borrowing? Working from right to left you say? Preposterous! Why would we subject ourselves to such nonsense that obviously no reasonably equipped child of the modern age would hope to comprehend when instead we can simply draw a picture and solve using only addition instead?! Why indeed?!

End of sarcasm.

Morons.

So here's the deal. The page said not to solve the problem, but to solve it using a number line. Now try REALLY  hard to think of an easier way to solve that simple subtraction problem using addition and a drawing.

Go ahead. I'll wait.

Tired yet? Me too. In the time that it takes to do it this way you could do 5 other subtraction problems. But I digress.

Here's a video that explains it, but I'll summarize. Basically you are to draw a straight line on your paper, and place the bigger number near the right end and the smaller number near the left end. Make sure you put arrows on the ends of the line to show that this is an "open number line". This is über-important. Now, the next step is to find some "friendly numbers" between these two numbers. I prefer friendly ones anyway, since unfriendly numbers are just mean, so I'm OK with this step. A "friendly number" would be something like 100. Or 50. Or maybe even 10. Basically I take "friendly" to mean whatever you can think of that is a good addition point for you. So if you're subtracting 63 from 237, you might choose 70, since you can easily add 7 to 63 to get there. Then you might choose another friendly number of 100, since you can easily add 30 to get there. Then you would choose 200, adding 100 to get there. Finally, you only have 37 to go, so your answer to the subtraction problem is actually the sum of these four numbers! See?!? We learned it all backwards! How do you subtract? You find the SUM of the DIFFERENCES between the friendly numbers in between! Brilliant!

OR you could just line the numbers up and just, oh, I don't know....SUBTRACT them. Good grief. And here's the cool thing - if you learn how to do it with two digits (i.e. borrowing), then you can do it for dozen digits. Hell, a million digits if you had time and inclination (Hint: you don't...).

What is wrong with these people crafting these lessons? What are we doing to our children? Are we so worried about their inability to do arithmetic we have to come up with a way to have them solve everything using drawings? Do we think they're so enamored with the visual world they are simply incapable of learning things without pictures? Well they aren't. They can and will learn what they are taught and they way in which it is taught. And if they are taught this crap, then they WON'T learn how to do the basic math. Who knew that we all took the ability to subtract numbers for granted? Kids are amazingly resilient if you challenge them. They will mess up and get it wrong - some more than others. This is normal and OK.

Incidentally, there's a part two of this rant. Apparently this Common Core stuff is also combining emotional hooey and math (and who knows what else). Not only did the original math problem in question ask to solve subtraction using a number line, but also provided an incorrect 'solution' by 'Jack' and asked the student to write a letter to 'Jack' explaining what he did right and then how to fix his mistake. That's right; you have to console poor, stupid Jack. I mean, 'challenged' Jack. You don't want to hurt the fake word-problem-figure's feelings. After all, HE PROBABLY LEARNED HOW TO DO SUBTRACTION THE OLD FASHIONED WAY AND GOT LOST ON THE DAMN NUMBER LINE.