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Sunday, October 21, 2007

Does this make cents to you?

Last Thursday, I spent about 10 minutes with one of my students on what I thought started out as a simple question.

She had written, "200 cents" as an answer for one of her questions. I asked her, "What is it another way we could say that?"

She stared at me uncomprehendingly. I tried to clarify. I said, "That answer is not wrong, but usually, when the number is that high, we use a different unit for money. Can you say 200 cents a different way, using that other unit?"

She thought for a moment and then responded, "200 dollars?"

Since cents and dollars are not the exact same thing, her response began the long, complicated discussion of how many cents are in one dollar. Getting that answer out of her was like pulling teeth. Teeth that apparently would have wildly fluctuating values for the tooth fairy.

I asked her to imagine that she had one dollar in her pocket, and I asked how many cents that would equal to. She corrected me, and informed me that she actually had seven dollars in her pocket. My mistake.

I tried a different tact. If she were to give me one of her dollars, how many cents what I give her for it to be a fair trade? One cent was her answer. I questioned that logic.

"So you could give me one dollar bill, and I could give you one penny, and that would be fair?"

Her head said no, but her eyes said she didn't know.

Her next guess was that one dollar was equal to twenty five cents. So I took a quarter out of my pocket, placed it on her desk, and asked, "This equals one dollar?"

"Four cents?" was her reply. Although she was grossly wrong, I thought I understood where that answer had come from, and that it meant she was at least stumbling towards the right path. Sure enough, when pressed further, she confirmed that she had gotten that last answer by adding the quarter four times.

So I asked her to write down twenty five cents four times on her paper and add them up. She did that and came up with -- gasp -- 100 cents.

"Yes, one dollar equals 100 cents," I confirmed. "So how many dollars with 200 cents be worth?"

"Seven dollars?"

At that moment, I honestly felt like I was stuck in the middle of a MasterCard commercial.

"Everyday Math Journal -- $1.50

Demonstration Quarter -- $.25

Incomprehensible Mathematics Conceptual Error -- $7.00

Bleeding Head Wound, Caused by Pounding My Head on the Surface of the Desk -- Priceless"


Matthew K. Tabor said...

I don't know whether to laugh, cry or do both!

I think I'll decide between the three by flipping a coin. You've got a 1 in 7 chance of guessing the outcome correctly.

Jules said...

ha! that is hilarious. in a very sad way of course. :) you should recreate it in photos and submit it to mastercard, just to give them a laugh and a peek at the real life of kids and teachers. :D

Chance said...

Holy lord flarking schnitt. How old are they again?

Anonymous said...

Sounds like she has the same conversion confusion as poor old cow is worth how many magic beans? But seriously, shouldn't she have learned how to do that in 2nd grade? I know they cover that in our second grades here.

Anonymous said...

well, this is going to cost you, but i taught my kids to count with pennies. when they made it to 100, no mistakes, they got to keep them, or could trade them for a one dollar bill.

this works for skip counting, too. nickels are 5's, dimes are 10's.

hope the DISD is paying you bunches! hang in there, and when is oprah picking up your book, btw?

Mister Teacher said...

Matt, I like my chances!
And speaking of chances, Chance, most of them are eight or nine.
Yeah, they're supposed to know that in second grade. And dang, Anonymous! You must go through a ton of pennies!!
Dunno when Oprah is going to get around to reading my book...

Nate Andrews said...

If this was a joke it would be funny. Alright, it is funny even if not a joke. On a serious note, recognizing this problem is there a way you could improve the student's math logic? It would be sad if stupid has become de-fault.

loonyhiker said...

Unfortunately I have been there with you on this one. I wish there was an easy answer to this one. Of course it leads to a future phase of why employees can't give change if the cash register is broken and doesn't tell them how much to give back!