[Maths-Education] Subtraction

[Alison Price]

I am not sure what Ian is suggesting here.
Is it that we should not do difference at all or that it should not be part of addition.  If
the latter than where would we site it in the currciulum?
I agree that it is difficult for young children to master the concept - as evidenced by
Judy's example, and similar ones e.g. where the difference between 8 and 0 is that 8 has two
round bits and 0 only has one.
Recording is also difficult as the words and the symbol sentences do not correspond. I
recently watched a student teacher (in his first practice) record 'the difference between 8
and 14 is 6 as  8 - 14 = 6'!
Perhaps too much emphasis on form (learning difference as a form of subtraction) rather than
context (how to find the difference, when) is too blame.

Alison Price
Oxford Brookes University


Ian Thompson wrote:

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> Judy Mousley wrote:
>
> Many 'difference' problems can be solved by adding on. However, the
> solution (while a missing addend) is actually the solution to a
> subtraction equation. (I know that's academic, but think about how an
> algebraic representation of the same sorts of problems would probably
> be solved.)
>
> The fact that we call them 'missing addend' problems, and write them 3 + []
> = 7 (with an addition symbol) surely strengthens my argument! And to solve
> it algebraically you would probably use 'inverse operations', just as you
> might use addition to solve a subtraction, so I don't think that invoking
> algebra clarifies the issue.
> Ian
>
> Ian Thompson
> Department of Education,
> University of Newcastle upon Tyne
> St Thomas St
> Newcastle upon Tyne
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> U.K.
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