I had a little extermination today. There was some dried fruit (a gift) that had gone bad. It wasn't good.
It was a good Thanksgiving; Skye hosted, her parents came from the midwest, and the VCs came from next door.
I started reading The Selfish Gene. So far, it is good.
There was some talk in the comments about how students strongly prefer decimals to symbols involving radicals or pi. I think that there are two reasons for this. The first is that the decimal gives students an idea of the magnitude of the number. The second reason is that students don't realize that there are multiple ways of representing numbers, and that the numerals that we use are merely symbols that represent an idea of a number, rather than the number itself. For instance, there is this idea that corresponds to the quantity of fingers on my right hand. We can represent this quantity as "5," "five," "V," "\sqrt{25}," or "cinco." These are all just symbols that represent the same idea. Students aren't generally too hip to this idea, and they prefer to stick to the symbols that they know: decimals.
Also, one of the perks of my job is that I get to field random mathematical questions from people around the question. Two months ago, someone called me to figure out the volume of a cylinder with a given radius and height. There was trickiness because there were conversions between "cubic feet" and "gallons" to be made. Now, I don't mean to brag here, but calling me to solve this problem is like using Agent Orange to tidy up the lawn.
I got a call last week from a couple of college students in Tennessee asking why a negative times a negative is a positive. Now, the proper way to answer this requires a bit of algebra. Instead, I gave the "If walking forwards is positive, and walking backwards is negative, what happens if you turn around (one negative) and walk backwards (the other negative)? You go forward." This satisfied them. It shouldn't have.
The proper way to see this is:
0=0
0=0(-1)
0=(1+(-1))(-1) (since 0=1+(-1) by definition)
0=(1)(-1)+(-1)(-1) (the distributive law)
0=-1+(-1)(-1) (because 1 is the multiplicative identity)
1=(-1)(-1)
I'm tired and out of ideas. I am going to watch Studio 60 and go to bed.
posted by Dirk Awesome @ 9:40 PM
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