In his LJ, Mr. Ibis posted an old gem about finding the height of a building using a barometer. The following was my rather long-winded response:
October 30, 2007
Ok, at the risk of spoiling a lovely story:
First off, I love this chestnut of a story. It's a terrific study in lateral thinking.
I think the "Neils Bohr" bit is a retcon; previously I saw it end on the "I will give you this fine barometer" line, which is a bit punchier.
But now I'm musing on the ending. I've been thinking about "bubble tests" lately, the SAT etc. I did very well on those, which was a lovely ego boost and a boon for college admission. I'm totally willing to believe there's only a so-so correlation between these tests and "smarts", but I'm unwilling to buy into the idea that "the only thing they test is how well you take tests". My current favorite (untested, but anecdotally supported) theory: there is a surprisingly strong correlation between reading speed and test scores. A number of people who I think of as clever, but they did poorly on the tests have said they aren't such fast readers. (Not sure if it's correlation or causation, but there are some arguments for the latter including being more able to check your work.)
But anyway, that's a tangent. My point was this: when taking a test it's good to be meta- about it. Often a thought about WHY they're asking a particular question, or providing those possible answers, is extremely useful. And I used to be a fighter; if I saw 2 choices that met the question as it was asked and got the right one based on a reading of the metaquestion, I would FIGHT for other kids who got the other "correct but not the right" answer, just because of my sense of justice and fair play.
So, I think asking a question with an "obvious right" answer isn't so bad. I would say that Bohr's other solutions all rely on having other props (a long rope, a stopwatch, a sunny day and a ruler, chalk and idiosyncratically architected stairs, string, rope AND a stopwatch, or a friendly and unusually knowledgeable superintendent.) Plus, several of them would probably cost you the barometer. I think the "correct" answer only requires the barometer and some knowledge. And roof access. But you get to keep the barometer.
Video of the Moment
I don't care who you are or what your life is like, it almost certainly doesn't have enough ninjas on roller skates: