Language, language…

Posted on September 22, 2017

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I was in full “beat head against wall” with adding integers with a student. ALEKS showed the problem 14.151 + (-27.345)  or something like that.   Its first “explanation” step said to do this:

27.345 – 14.151

My student wanted to know why the signs had changed.   I’m reasonably positive that the idea that this wasn’t the same as the original problem wasn’t understood… the difference between signs and operations… oh, and English not first language. How many times did I try to explain that it was written in that order because *we don’t subtract big from little.*   I mean, we don’t by hand (ALEKS did have a picture of doing the actual subtraction and I tried to explain that it didn’t make sense w/ numbers switched)… of course we do in the calculator…

I left that road and went to “what does student know that I can relate this to?”

3 – 6 was known to be -3.  I elicited explanation of why…   Established that 3 + (-6) had same result as 3 – 6 … that opened the door… and no, I didn’t fully understand the explanation but it was mathematical, not a some weird trick and … things are better now 🙂

Still… solidifying in my little brain the value of knowing same sign addition to automaticity…

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