## Friday, February 13, 2015

### Five Things You Need to Know About Algebra, Part V

(Click on the comic if you can't see the full image.)

I still can't believe I wanted to do this all in One Day as a Mega-comic.

As for the math: you'll notice that I actually left it out of the comic. I never heard "PEMDAS" until I became a teacher ... for a couple of years, no less. I learn Rules. Having a nice little code was nice at first, until I realized that students didn't understand the meaning behind the letters. Sure, they knew two things that they stood for, but the words didn't mean much to them. Worse, there was insistence that addition must come before subtraction, which isn't true.

Moreover, there are omissions. Where do the absolute brackets go? Well, there like Parentheses, but they aren't the same thing -- don't try any fancy Distributive Property stuff. And what about Factorial? Is it multiplication? No, it's more like exponentiation!

55 = 5 X 5 X 5 X 5 X 5
5! = 5 X 4 X 3 X 2 X 1

However, not the same thing because, for instance, 32 X 22 = 62 but (3!)(2!) =/= 6! -- and I'd like to add another exclamation point for emphasis!

By the way, I meant what I said about "two" things. I drew this Halloween comic (from 2007) on the board, and I student told me, "It's DEAR Aunt Sally! Don't you know anything?"

Could've been Aunt Silly for all that it mattered. And it was silly.

Dan-NC said...

Just a general comment. x, why? is one of several geek-oriented comics I read. I hope your students do too.

I'm a business analyst who uses high school algebra to amaze my boss and coworkers. I get paid well. So when your students ask, "When am I ever going to use this stuff?" You can tell them, "When you want to collect a pay check."

BTW: I originally hail from Ridgewood. My wife is from Flatbush, down by the Junction.

(x, why?) said...

I know the Junction well (or at least, I did). It's a block away from Brooklyn College and (long) before those days, I used to catch the train there to visit my grandfather ... who was still a mile or so walk away from the terminal.

Thanks for the kind words!