Drinking the Kool-Aid

Closing the Teach For America Blogging Gap
Jan 07 2011

Take Away

This afternoon, I had two goals for my hungry student: 1) find missing lengths of right triangles and 2) find various areas of composite figures. We were working on the latter, and came across an interesting problem; instead of being given the triangle’s lengths, you were given other measurements that could lead you to deduce their lengths.

We’re looking at this problem, and it’s been established that “this whole length is 25m, and this part says that 5m of that is already taken up. So what part is left for the base of the triangle?”

She couldn’t tell me. She started fidgeting and doing this nervous rocking thing she does, and I knew I needed to say it a different way. So I say, “let’s say I’m standing here, and you’re standing 25 meters away from me. If I walk 5 meters toward you, shortening that distance, how far away am I now?”

She narrowed her eyes and looked at me, and said, “isn’t it just… 5?”

“Well, if it was 5, then that would tell me that this 5 meters plus the 5 meters I just walked would add up to the total 25 meters. But I know 5 + 5 isn’t 25…”

Fidgeting, rocking more, and a murmur: “… that’s tricky…”   (adorable)

Sigh. I gave in.

“So if I have 25 meters and I take away 5 of them, how many do I have left?”   She immediately typed 25-5 into her calculator (yes, you read that right) and said, “20?”

The vocabulary of math is crucial. And crippling. She heard those key words “take-away” and knew that meant “push the minus button.” She could connect “take-away” to “subtract” but couldn’t connect either of those words to the actual concept of a number of meters being reduced by a certain amount. Even “take-away” has become a meaningless memorized term, something that obviously started out to ignite real understanding, but memorized to the point that it’s now just another math word. So when I’m trying to scaffold down to meet them so they actually get it, I run into these land-mine key words that clue them in to some prior math-class knowledge and screw everything up. It’s really weird to have to come up with ways to explain the concept of subtraction without saying the words “take” and “away” to close together. Crazy. What do they think “Take. Away.” means?

5 Responses

  1. G

    This week, I taught double digit subtraction with regrouping to my 2nd graders. They could not grasp the word or the concept of “regrouping.” So I made up a story about having to “borrow something (10) from the neighbor (the tens column).” They got it right away when I explained it to them like that. The problem now is that when I have them write down the steps involved in regrouping, they tell me the “borrowing from the neighbor” story every time, with absolutely no mention of the word “regrouping.” At least they’re grasping the concept…I’ll take it…for now!

    • Wess

      Haha! I learned it as “borrowing” anyway!

  2. Those cute stories always helped me as a student and helped my students as a teacher. Experienced math teachers should have a ton built up and you will develop your own as time goes on. Here is one trick I learned from a fellow teacher when I taught fourth grade. (I realize that you teach a much older grades, but it’s clear that you are dealing with some really low-level kids, some of whom could use help with basic math skills.) Sometimes kids will end up one number off when they subtract, because they use their fingers to count and they count the original number as part of the problem. You can solve this problem by telling them to say the original number out loud, then having them count up to the higher number and make a dot on their paper for each number. Then they count up the dots and the number should be the correct answer. It helps them imagine subtraction conceptually. Will that get your high school math students ready to pass TAKS? Probably not… but it looks like you are seeing progress, so take it for what it is, and keep learning those tricks and explanations from fellow teachers.

  3. cindy tennant

    This is high school? so sad that most of the learning years of this child have been wasted.

    • Wess

      “Taken Away,” if you will. :P

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Region
San Antonio
Grade
High School
Subject
Math

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