### It's all math, all the time 'round here

One more tidbit gleaned from the training session. Up to third grade (or fourth? I can't remember) the kids are allowed to draw bar graphs with the bars touching. After that, it costs them a point if they use touching bars rather than separating them. Unlike the equations/expressions and strings issues, where I could at least guess why it mattered, even if I thought it was a bit harsh, I have no idea why this one matters, mathematically speaking. I got lots of great comments on the last post, clarifying some of the test-designers' reasoning - got anything for me on this one?

## 7 Comments:

If losing points because the bars on bar graphs touch doesn't tell you there is a touch of insanity inside the groves of academe, what would?

Go wild and let the "error" go unpunished.

Meanwhile, I've never sat for a PowerPoint presentation during which the presenter was criticized for the propinquity of the bars on his bar graphs.

Maybe it's a violation of one of those Edward Tufte rules for visual presentations -- separated bars make the differences in the height more proportional to the differences in width, or something.

Or maybe somebody figures teachers haven't got enough to do already.

It's to distinguish between true bar graphs and histograms. True bar graphs show category data (eg. how many in each category: how many people have cats, how many people had a sandwich for lunch), and the bars in the bar graphs should be separate because the categories are separate.

Histograms show numerical data, and generally data in a range (eg. how many children are between 46 and 48 inches tall). In a histogram, the bars are supposed to touch to represent that the bar includes data from a range of values.

It makes sense once you do some histograms (and work with some pre-service teachers who don't get the difference between categorical and numerical data), but I do worry how many 4th grade teachers understand the distinction...

"histogram" versus "bar chart"

has become quite an issue

in intro-statistics books ...

unfortunately ... but the idea

*ought* to be very easily understood.

butting the bars up against each other

implies that the data are measured

on a

continuousscale; separating 'emimplies that the scale is

discrete.a classic example of the difference

is "foot size"

versusshoe size:my foot may be 11.37 inches long

but i'm darn well gonna have to choose

between an 11 and an 11-and-a-half size shoe.

the powers that be in math ed have decided

that making an enormous fuss over non-issues

is vastly more important than actually

trying to teach students mathematics.

this is a pretty typical example.

http://vlorbik.com

Yep. Histograms vs. bar graphs.

I'm actually surprised they allow it up to a certain point. That's kinda mean, don't you think? "Go ahead and be wrong now, Johnny, but just you wait 'till next year. Just you wait! HA HA HA HA HA!"

Tests are instructive as well, and allowing students to learn something that they will later have to unlearn is, in my opinion, mean. But it's everywhere in elementary math education.

If they don't want students drawing bar graphs with the bars touching, but are also not willing to tell students that yet in the lower grades, then revise the test in those grades to make it impossible to draw touching bars. Or, you know, just tell 'em. That's not going to break their thinkbones, I don't think.

I came to say I don't know, I use Excel or another SS to chart my graphs.

Ms. Frizzle;

Is that why we can't find the forest because the trees are in the way?

In my high school I am just happy they can plot data on a graph. Line, circle, bar, histograph. it is pitiful that 10th graders don't know the difference between a dependent and independent variable, a direct vs. an indirect relationship.

I spend the first monrh (September) of the Earth Science class on understanding and applying graphing. This is necessary because the 10th graders come in to my class with no graphing skills! Who is at fault? The 9th grade Living Environment teachers? the math teachers? the middle school teachers? I don't know However,the students tell me that they finally understand graphing after a month of applied graphing (hurricane tracking is their favorite activity) and I don't have graphing problems when they take the Regents in June.

What's the answer? I suggest that at the 5th or 6th grade level that graphing be applied to real-life situations to make it relavent to the students so that they can retain what they learned.

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