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The Bad and the Ugly #2

This one was spotted in a school's 'maths specialist room'.

It seems from this information poster that '=' can mean "same as", "equals" or "Total"... two out of three aint bad. The "Total" part is clearly nonsense of course because we already have a perfectly good sign for that (+).

= means "equals", "Equivalant to", "is the same as" or "balances".

Luckily we managed to get the poster taken off the wall straight away.

equals equals a mistake

If you've spotted anything that is erroneous and annoying feel free to moan about it in the comment box below. I'd love to hear your thoughts.

- Bad and Ugly

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8 Comments

Re the comment on using the

Submitted by CecKitKat on Sun, 11/18/2012 - 15:17.

Re the comment on using the same as. If I have 3oranges and 4 apples I have seven fruits but they are not the same. If we use the correct terminology then there will be less confusion particularly for children with additional difficulties and later when we use numerals as nouns when tackling algebraic equations. where a + b = c but is not c. Additionally when we say that 2p + 2p +1p is 5p it is not but has the equivalent value. and in this case not at all quantity where in fact there are 3 coins equivalent to 1 coin.

I'm very hot on using

Submitted by johdu on Wed, 11/21/2012 - 00:38.

I'm very hot on using vocabulary accurately... without that we are in danger of confusing all the students and children we work with. I'll leave the last word on this to Barry Mazur of Harvard - this is well worth a little study:

When is one thing equal to some other thing?

The maths symbol = does not

Submitted by CecKitKat on Wed, 07/11/2012 - 22:51.

The maths symbol = does not mean 'the same as' It actually means is equal to, equals or balances but definitely NOT 'the same as'. For example 3+2 is equal to 5 but it is still 3+2. It does not mean 'makes' either because it is still 3+2. This is important to acknowledge when writing in equation format 3+2=5 similarly when using algebraic equations a+b = c when a+b is clearly not the same as c but is equal/equivalent to c. This also applies when dealing with money. 3pence + 2pence is equal to 5pence but is not a 5pence coin therefore we cannot use the term 'same as'. Rant over.

CecKitKat, While I clearly

Submitted by johdu on Fri, 07/13/2012 - 00:07.

CecKitKat,

While I clearly agree with you in some parts here, I think you are confusing common 'day-to-day' usages with mathematical ones. The technical (mathematical) definition of equality is the state of being "quantitatively the same... Being the same or identical to in value". Therefore, it is both reasonable and correct to say that 3+2 is "the same as" 5, if we are speaking in terms of value (which we are). Similarly, any good shopkeeper will tell you that 3p plus 2p is the same as 5p! If we were to follow your argument to its logical conclusion we would have to say, when faced with two 5p coins, that the first 5p is not the same as the second 5p ... since the first is a different coin (I'm sure there's a joke puzzle based on this type of misconception). This, however, is the common 'day-to-day' meaning of same as, not our mathematical one. Likewise, confusion could be had with the use of 'similar' in geometry, where again the term does not match 'day-to-day' usage. Vocabulary is extremely important, and we must get it right to help our young learners fully understand the logic and beauty of mathematics.

My initial argument with the poster maker was that '=' cannot ever mean 'Total' - with that, at least, I am sure we both agree.

On a positive note, I returned to the school a few weeks later and found that the poster had been removed. So all's well that ends well.

John