[Edu-sig] Order of operations confusion

[Laura Creighton]

In a message of Thu, 05 Mar 2009 15:19:52 MST, Charles Cossé writes:
>On Thu, Mar 5, 2009 at 2:52 PM, Laura Creighton <lac at openend.se> wrote:
>> In a message of Thu, 05 Mar 2009 12:51:40 MST, Charles Cossé writes:
>>
>> The interesting question (to me at least) is whether he would be willin
>g
>> to rewrite a + b + c  as a + c + b
>>
>> and then if he would be willing to rewrite
>> a + b as a - (-b)
>
>
>
>
>Yes, I confirmed that it was definitely due to having been repeatedly
>told the simple rules for order of operations; he observed that "there
>was something to be multiplied" and believed that he couldn't proceed
>until he had carried out that multiplication, which immediately led to
>a gridlock situation for him ... and he would have been okay rewriting
>like you did there since there was no multiplication.  Guess it's just
>one of those many things that you don't realize kids think until you
>come across it ... and then it's a surprise
>
>Charles


I'm teaching 10 and 11 year olds here in Sweden, but over the summer
holidays or on weekends in optional classes.  I am always curious as to how
the rest of the world teaches things.  Can you ask him for a favour
for me and see if he would be willing to accept that:

82 + (15 * 10) - 51

is the same as

(15 * 10) + 82 - 51

or if the * is really stopping him cold.

And thank him very much for me for answering my question, if he is 
willing.

Laura