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Monday, October 27, 2008

Fuzzy math

I got a new kid in my class last week who really can't read, and I'm still a little iffy on his math skills. The first day he was with me, we took a test, and looking at his answers made me really question his methods.

The thing is, it's true when they say that there are multiple correct methods to get to the correct answer. I just don't think I had ever seen the method that this kid utilizes. He apparently does a math problem the same way Billy from Family Circus runs all over the neighborhood, following that convoluted dashed line.

An example problem:

The test was mostly over simple subtraction. One of the questions was 99-69. The good thing is that this boy shows his work on his paper, so I was able to CSI it and do a little forensic math investigation to track back how he solved the problem. As near as I can tell, here is how he solved 99-69:

First, he stacked the numbers up, as he should:

Next, he looked at the Ones place, saw 9-9 and decided to regroup (or borrow). So he crossed off the 9 in the Tens place and made it an 8. Then he crossed off the 9 in the Ones place and made it a 19.

He subtracted 19 - 9 and got 10. So he put the 0 in the Ones place of the answer space and regrouped again (carrying the one this time). Now, he had an 8 AND a 1 up above the Tens place, so he added them and got 9. He then subtracted 9 - 6 and got 3, which he put in the Tens place.

Voila, his answer was 30, the correct answer.

Oh, and did I mention little "sticks" were everywhere, enabling him to do the actual subtraction and adding of each step?

I think if I give this kid 9 hours for each test, he will do OK...


The Bus Driver said...

haha that method made my head hurt, but hey he got the right answer!! even if it was in a roundabout way!

Unknown said...

I love this kid!
Also, maybe he is using a similar strategy as he reads, so instead of looking for shorter words or syllables to decode hard words, he is doing it the other way around, so when given the sentence "The cat is on the mat" He comes up with "Theology catamaran island ontology thesis maturity"

BethTex said...

Reminds me of the old Tom Lehrer song "New Math"
At least it shows he understands the basic concepts :)

Anonymous said...

Sounds like our kids suffering under TERC's Investigations Math! My 3rd grader tries to subtract the larger digits from smaller in each column, no matter which one is the larger "number". I tried to teach her how to "borrow" but she gets so frustrated she cries! She only gets the correct answers when she uses the "special" Investigations problems that are easier (nothing over 2 digits and often not that hard) and work with simple regrouping. Any harder numbers and she crashes...

Ms. Longhorn said...

LOL I see a similar thing happen when students come to me having learned lattice multiplication. It's an interesting technique, but in my mind is so tedious and time consuming!

Anonymous said...

Ah yes, the joys of leftover Everyday Math skills! I couldn't figure out what in the world one of my third graders was doing until one day I saw him. The problem was something like 59 + 83 and I saw him look up at the number line on the wall and yup, you guessed it, counting. He started at 59 and went on from there. When I moved down to 1st grade the next year (thank GOD) I found out why he did it that way. That's the way they teach it in third grade. I'm soooo glad we don't have EM anymore!!!!!

Anonymous said...

ok...I typed really fast and didn't me! I'm on vacation!!! lolol