Math Is Fun Forum

paulb203

Member

Registered: 2023-02-24

Posts: 261

Linear graphs (skewed)

I've noticed that, on Maths Genie at least, the graphs are often skewed because the squares alloted to the value of 1 vary from the x axis to the y axis. For example the x axis might have two squares for the value of 1, and the y axis only one square for the value of 1. I noticed this when the gradient didn't look right.

I know sometimes they have to do this for the graph to fit on the page, but I looked at several examples, re-did the graph with equal squares alloted to both axes, and it fitted fine. And, obviously, the gradient then looked right. So why do they do this? And is it common elsewhere? And, does it skew anything else?

Phrzby Phil

Member

From: Richmond, VA

Registered: 2022-03-29

Posts: 45

Re: Linear graphs (skewed)

A terrible idea.  Visualizing slope is so important, especially to beginners.

My hand-held graphing calculator also has non-equal vertical and horizontal spacing, which I point out to tutees and urge them to use websites that do this correctly.

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World Peace Thru Frisbee

Bob

Administrator

Registered: 2010-06-20

Posts: 10,524

Re: Linear graphs (skewed)

When you're learning about y = mx + c it's a big help to have equal scales but there going to come a time when you have to deviate from this.

eg y = 1000x + 100.

The MIF function grapher has equal scales.

My ideal would default to equal scales but give the user the option so rescale each axis.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

paulb203

Member

Registered: 2023-02-24

Posts: 261

Re: Linear graphs (skewed)

A terrible idea.  Visualizing slope is so important, especially to beginners.

Thanks, Phil. And yes, it's important for it to make sense, and for the student not to just go through the steps to get the correct answer. Some might say they don't care, they just want the correct answer, but even for those the more they understand it the more they will get the correct answer.

paulb203

Member

Registered: 2023-02-24

Posts: 261

Re: Linear graphs (skewed)

When you're learning about y = mx + c it's a big help to have equal scales but there going to come a time when you have to deviate from this.

eg y = 1000x + 100.

The MIF function grapher has equal scales.

My ideal would default to equal scales but give the user the option so rescale each axis.

Bob

Thanks, Bob. Yeah, I get that we can't always have equal scales. And I'll check out the MIF grapher.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,524

Re: Linear graphs (skewed)

https://www.mathsisfun.com/data/function-grapher.php

B

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

paulb203

Member

Registered: 2023-02-24

Posts: 261

Re: Linear graphs (skewed)

Thanks, Bob.