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Topic:  Is "variable" confusing to students? 
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Subject:  RE: Is 'variable' confusing to students? 
Author:  Peggie 
Date:  May 8 2009 
I agree that if you use the word "variable" to mean "something that varies" it
can be confusing to students. In teaching 7th grade math, I simply define a
"variable" as a letter that stands for one or more numbers. While that may be
simplistic, it does work in all three of your cases  the expression, the
equation, and the slope equation.
On May 8 2009, Susan wrote:
> I'm trying to establish the differences among the following three
> things:
3x + 5
11 = 3x + 5
y = 3x + 5
The first is an
> algebraic expression containing the "variable" x. In this case, the
> variable x can take on any value. It “varies”.
The second is an
> equation of one variable. We call x a variable but truly it doesn't
> vary. It is just an "unknown". We can solve for x and determine it
> must equal 2.
In the final case, we have two variables and they
> do 'vary' depending on each other’s values.
Should we call the x
> in the second case an “unknown” and not a variable? I’ve seen
> books say, “solve for the unknown”.
I think we confuse students
> by calling x “variables” in all of these cases when in case 2, the x
> does not vary at all.
 
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