Rules Rules Rules

Posted on September 5, 2017


Mainly I’m doing the time-honored “find that powerpoint file so you can do a better video.”   Looked to youtube to see what’s out there already and found several “here are the rules!  This is EASY!!!”   — breaking two of *my* rules.  Don’t tell me it’s easy just because it’s easy for you!  and … teach to understanding.   Basically, this is easy *if* you either have a good rote memory and don’t care what you understand, or you already grasp the “oppositeness” of negative numbers.   If for all your life adding has meant things got bigger, then no, this is not going to be intuitive (a.k.a. “easy.”)

Helping With Math  at least has an elegant summary with a number line.

I found this with videos of two primary kiddos (first and second graders) who correctly figure out subtracting and adding negative numbers in completely nasty equations, using number lines.   I resisted the “oh, they must be brilliant children!”  path and pondered whether it’s harder to teach this stuff later when there are so. many.. rules.    The girl’s logic for 2 – ??? = 6 was that with negatives it always went the other way.   So subtracting a positive would go that way, so subtracting a negative would go this way.   The kiddos spent time with the number line, thinking and pointing and moving.

This aligns with my idea that “opposite” is enough to grasp negatives and positives, and lots of folks who might struggle with advanced abstractions could handle this one… but we need to give ’em time to think and point and move…  and it makes me question the benefits of “hot air balloon” models.   Hmmm.

(Yes.   This also confirms that idea that  positivity and negativity are about position… )