Two wrongs don’t make a right :)

Posted on September 5, 2014

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…. but that’s a good thing! 

    I’m going to try this as my experimental response for the student who is tuned for the “rule mnemonics.”   

I’m all for nixing tricks per http://nixthetricks.com/ … but many of my students didn’t have teachers who made sure they understood math, so they arrive here very, very practiced at reciting mantras and using tricks.   I can give them chapter and verse for gains and losses, ups and downs… but -3x + -4x is 7x because “two negatives make a positive. (Yea, it’s ALEKS ;))

    So… my response has become “but two wrongs don’t make a right when it’s adding and subtracting.”  Then “you start out behind 3 and back up 4 more… ”   (I’m also trying to hone the language so that the first number is a starting point, instead of saying ‘you lose four and you lose four more,” because that first thing that looks like –   is a negative sign, not subtraction.)   

   

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Posted in: ALEKS, math