Tuesday, April 6, 2010

Don't teach if you don't know

I may not have the most finely-tuned pedagogical technique, but at least I don't get basic shit wrong, like this:
Some years ago, my (now ex-) wife was involved in a "trivia night" fundraiser at
her elementary school, and they wanted me on their "teacher team" to round out
their knowledge. They had almost everything covered except some
technology-related topics and I was an IT guy. In round four, my moment to shine
arrived, as the category was "Math & Science" and one of the questions was,
"give the first five digits of pi." I quickly said, "3.1415." The 9 teachers at
the table ignored me and wrote down "22/7" on scrap paper and began to divide it
out. I observed this quietly at first, assuming that 22/7ths gave the right
answer for the first 5 digits, but it doesn't. It gives something like 3.1427. I
said, "Whoops, that won't work." They ignored me and consulted among themselves,
concluding that they had all done the division properly on 22/7ths out to five
digits. I said, "That's not right, it's 3.1415."

What follows is some neat storytelling on the escalation of the argument. It is revealed that the hero of the story (Mr. 3.1415) has an English degree, and (god help us) one of the "22/7 stooges" has a flippin civil engineering degree. Ultimately the teachers (who insist that 22/7 is the "correct" value of pi), get out the textbook that started this falsehood:

A great murmur arose at a few other tables as well, and my wife returned
with the text book. The teacher with whom I had been butting heads the most
grabbed it, thumbed through to the area of a circle chapter, jabbed her finger
at a sentence, and shoved the book across the table at me. The sentence said,
"Pi is an irrational number approximately equal to 22/7ths." The teacher sat
back, crossed her arms triumphantly, and said, "I hope they taught you to read
with your English degree." I read it, and slid the book back across and said,
"They also taught us to read the footnotes." As she read looked back at the
page, the blood drained from her face. At the end of the sentence was a little
"1" in superscript, and dutifully noted in the footnote were the first 20 digits
of the actual value of pi. Of which the first five are 3.1415.

Ok, so they don't know the analytical definition of pi. Surely they haven't seen the proof that 22/7 > pi, like this one. Great. But, in this case, they're just not reading, or maybe don't know what "approximately" means, or maybe too damn lazy to read a footnote.

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