Now, as an adult with a college degree, I have memorized over the years the fact that 32-12=20. And I can also write it out using the standard formula. But now let me make something very clear to you. I never understood math. I struggled with it all through school, and as soon as I had the chance to drop it, I did so. I recall an argument I had with my mom when I was first learning to subtract. I was adamant that 1-1=1, not zero. (I was in the first grade, cut me some slack). I finally just accepted the fact that I was never going to really understand math, and just needed to memorize what I was being told, whether it made sense to me or not. Subtraction with carrying? Forget it. To this day, I still don't understand WHY subtracting one number from another and adding it to the next turns a zero into a 10 (instead of a 1). (like 100-33. Cross out the one, stick it next to the first zero, to equal 10, then cross it out again to get 9, add the extra digit to the final zero to get 10 so you can subtract 3 from 10, instead of 3 from zero, and 3 from 9, instead of 3 from 0.) I just know that's what you do. So now you know where I am coming from. Math makes no sense in my head. Just memorize how to do it, and move on. But this common core thing? It makes sense to me. That in and of itself is a small miracle.
Let me tell you why. I'll explain by answering the last of the questions raised on the video. "Where do they get the random numbers to add together?"They don't just magically pull them out of the air, I promise. When they tell a child to add 12+3=15, they are showing them how to get to an easier number to deal with. I know automatically that 15+5=20. 5's are easy to work with. But I have to do a little bit of mental math almost every time when I try to figure out what the difference is between 12 and 20. The mental math I do? 20-5=15, and 15=3=12. 3+5=8. Exactly like how common core is teaching these kids. Now, once they are at 15, it's far easier to make the jump to 20, then 30. and the number 2 is obvious, because that's all that's left. Does it take longer? Yes. But if this shows kids how to break down math into more manageable numbers, so that there is less confusion, less memorizing, and more reasoning, then good for them!
3 comments:
The problem, I think, is that what makes sense to you does NOT make sense to a majority of people. I still can't figure that out, and I read your explanation twice. So do we turn the way we teach math on its head, and confuse the majority of students? I would suggest instead that teachers be prepared with this kind of alternate thinking, so that it can be used as an aid to those students who aren't understanding the standard explanations.
Yeah, the way Abbey is describing this problem, they're counting UP from 12 to 32, rather than taking 12 away from 32. It's the way cashiers always give you your change back from a purchase. If you give a $20 bill for an $8 purchase, the cashier puts 2 $1 bills in your hand and then a $10 bill and counts out loud, "9, 10, 20" as she does it...counting UP from 8 to 20.
Yeah, the way Abbey is describing this problem, they're counting UP from 12 to 32, rather than taking 12 away from 32. It's the way cashiers always give you your change back from a purchase. If you give a $20 bill for an $8 purchase, the cashier puts 2 $1 bills in your hand and then a $10 bill and counts out loud, "9, 10, 20" as she does it...counting UP from 8 to 20.
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