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How important are number lines?


MeaganS
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Both of my kiddos have struggled when math programs ask them to add or subtract using a number line. I don't know if I'm just not teaching it well or not, but even my stronger math daughter, who shows a very deep understanding of what is going on with numbers, gets frustrated when forced to use a number line. And I'm not sold that counting hops backwards and forwards is that important of a skill. If the child understands the comparative value of numbers, is there any inherent good in focusing on number lines for solving addition and subtraction problems?

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Both of my kiddos have struggled when math programs ask them to add or subtract using a number line. I don't know if I'm just not teaching it well or not, but even my stronger math daughter, who shows a very deep understanding of what is going on with numbers, gets frustrated when forced to use a number line. And I'm not sold that counting hops backwards and forwards is that important of a skill. If the child understands the comparative value of numbers, is there any inherent good in focusing on number lines for solving addition and subtraction problems?

 

My only question would be whether she's frustrated because it doesn't make sense to her, or frustrated because it's a pain in the neck?

 

If she has a deep understanding, I'd guess it's the latter.  If so, I agree - not something that needs to be focused on. But if the concept is confusing, it could indicate that there's something she's not understanding.

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Both my kids disliked the "counting up" and "counting down" lessons w/ number lines in Singapore. They understood them, but didn't think about numbers that way.

 

I'm pretty good at math and I think of numbers on a line, although it's more like a vertical spiral staircase than a straight horizontal line. But I really hate numbers in a grid, like 100 charts. Tracking numbers across broken rows and columns drives me nuts.

 

So to each his or her own, I think there are lots of ways to grok numbers and if the line doesn't work, I would ditch it.

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I agree that they aren't really a tool many kids need until they get to negative numbers.

 

I think a lot of kids find them frustrating because they're too easy. As in for them it's like being asked to prove the apple is red or that the temperature is warm or something - it's just too obvious.

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Echoing Farrar, I think number lines are too intuitive and thus frustratingly boring/obvious for some kids, especially those with a good math sense.

Two exceptions I can imagine:

1. Teaching fractions of whole numbers. Or: ruler math!! Visualizing numbers as continuous, rather than discrete, is an important skill that number lines do well. The difference between continuous/discrete is hugely important as students move into topics like statistics, for example.

2. Addition and ***subtraction*** of negative numbers. Especially subtraction. Especially if you have a kid who wants to know why "minus a negative means plus a positive." 

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Some math programs like RightStart never use a number line as a tool for doing adding and subtracting. I don't think my DD ever saw this method until we switched to CLE in 4th grade and they used it for negative numbers (I think toward the end of the 400s somewhere). It didn't diminish her math understanding at all I don't think to not use it until later.

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I had a math professor tell me that number lines were actually created as a tool for students that don't conceptualize math well. My child has a strong conceptual understanding of numbers and value but the number line has never made sense to him. The only time he seems to see its purpose (and I tend to agree with him) is when he's using a ruler or graph. I do see how it would be useful in negative numbers but we have not reached that concept yet.

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At 7 or below, not important.  But, I do think they become important when kids hit prealgebra / algebra.  Then, you need to understand what it means, and not just know how to add/subtract.  Of course, at that point, the kids are getting ready to graph, and you've got to have number lines for that!

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I will take a number line over a 100 number chart or a 1000 number chart. My son's school uses Everyday Math and they have to fill in missing numbers on the chart over and over and over again. Then they teach them how to add and subtract by going down/up and right /left using the chart.  My son hates it.  He just started third grade and had three pages of homework involving the number chart. He always asks what is the point since he can already add and subtract thanks to other math programs that I teach him at home. 

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We rarely use a number line. The few times I have wanted to explain a concept to DD where a number line would be handy I have used a meter stick and c-rods. It works really well for things like skip counting and DD loved it.

 

 

Sent from my iPhone using Tapatalk

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Number lines are certainly useful for some kids, but I suspect that making every kid use them extensively is just the current fad. I don't remember ever encountering them during my 13 or so years of school math. All my kids figured out negative numbers on their own before we "got to them" in math. 

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I haven't worried about it. My dc have all been really strong in math, and didn't find number lines very helpful when they were first introduced. They pretty much ignored them and just answered the addition and subtraction questions. When the number lines were used again to introduce negative numbers and fractions, my dc found them a little more helpful.  

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