Sniffnoy comments on Learned Blankness - Less Wrong

130 Post author: AnnaSalamon 18 April 2011 06:55PM

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Comment author: SilasBarta 18 April 2011 07:29:38PM *  28 points [-]

Great article! I didn't realize how I blank on some of those.

When I tutored math, new students acted as though the laws of exponents (or whatever we were learning) had fallen from the sky on stone tablets. They clung rigidly to the handed-down procedures. It didn’t occur to them to try to understand, or to improvise.

I'd like to self-centeredly bring up a similar anecdote, which forms part of my frustration how people give unnecessarily-complex explanations, typically based on their own poor understanding.

In chemistry class, when we were learning about radioactive decay and how it's measured in half-lives, we were given a (relatively) opaque formula, "as if from the sky on stone tablets". I think it was

mass_final = mass_initial * exp(-0.693 * t / t_halflife)

And students worked hard to memorize it, not seeing where it came from. So I pointed out, "You know, that equation's just saying you multiply by one-half, raised to the number of half-lives that passed."

"Ohhhhhhhhhhhh! It's so much simpler that way!" And yet a test question was, "What is the constant in the exponent for the radioactive decay formula?" Who cares?

Sandra runs helpless to her roommate when her computer breaks -- she isn’t “good with computers”. Her roommate, by contrast, clicks on one thing and then another, doing Google searches and puzzling it out.[4]

Wow, a footnote on this one and not even a link to the xkcd about it? ;-)

Comment author: Sniffnoy 19 April 2011 01:48:15AM *  8 points [-]

I have to say, if I saw anyone write the equation that way I'd question how much they understood the concept themselves!

EDIT: Let me also add, if I saw anyone asking that "what's the constant" question, I'd conclude they didn't understand it unless I saw good evidence otherwise...

Comment author: SilasBarta 19 April 2011 02:31:30PM 5 points [-]

Just to brighten your day, that would be most teachers and probably most textbook editors.