Math Arguments

Dirt Triangle

Taken from David Cox, changed just a little:

While I was out, I left a few distance/rate/time problems for students to solve.  Upon my return, I was asking students about the problems and many students had similar responses.

S:  "The Dirt Triangle."
Me:  "?"
S:  "Look, Mr. Cox it's like this...


"...You cover up the one you're looking for and if the other two are next to each other, you multiply.  If one is above the other, you divide."



Me:  "Really? That's strange.  I never learned the Dirt Triangle. I learned ... The Turd Triangle



S₁: "No, that won't work. That's not what he told us."
S₂: "He said it didn't matter how we wrote it."

Me: "So which is it; does one work or are they the same?  Make your case and be ready to defend it."