dxmachina: (teaching 01)
[personal profile] dxmachina
I like start each lecture with a quote or cartoon or something similar on topic to what's going to be covered. (I used the cartoon in the icon in my first lecture.) Sometimes they're funny, sometimes they're pithy, and occasionally they are filks, like this one I did last night on the ideal gas law (PV=nRT):

One law for Boyle, with extent versus spring,
One more for Amontons, T zero was the thing,
Another one for Charles, expanding in the heat,
And one for Avogadro, with particles discrete,
In the Realm of Gases where the volumes change.

One Law to rule them all, One Law to find them,
One Law to join them all and through a constant bind them,
In the Realm of Gases where the volumes change.

I just wish there was some property of gases that would allow me to make the last line a little more sinister, but ideal gases don't really have shadows.

I've done of couple of others that I liked. One was about the octet rule, something to remind the students to count the number of electrons arrayed about each atom in a Lewis structure (there should be eight, no more, no less). Over many years of teaching this stuff, I see so many students forget to check their work, and it gets especially frustrating when all they need to do is count. I mean, you can check the octet rule even if you're missing two fingers. Not counting leads to all sorts of chaos when they make the attempt, so I tried to help:

And the Lord spake, saying, "First shalt thou count the electrons. Then shalt thou count to eight, no more, no less. Eight shall be the number thou shalt count, and the number of the counting shall be eight. Nine shalt thou not count, neither count thou seven, excepting that thou then proceed to eight. Ten is right out...

In the class on dimensional analysis and problem solving techniques, I used the following problem to demonstrate that sometimes one has to wade through a lot of extraneous material to get to the root of the matter:

A More Complicated Problem...

Scene – Behind a wall outside the castle gate...

Westley: Where can I get a sword? How much will it cost? Can I afford it?
Inigo: Let me sum up. Buttercup marries the Prince in an hour. There is a sword available online, so all we have to do is log on, buy the sword, pay for it, save Buttercup, and make our escape.
Westley: That doesn't leave much time for dilly-dallying.
Fezzik: You just wiggled your finger. That's wonderful.
Westley: I've always been a quick healer. What are our liabilities?
Inigo: The seller insists on being paid £125, and BruteSquad.com has no automatic conversion function from pounds to dollars.
Westley: And our assets?
Inigo: Your brains, Fezzik's strength, my steel, and $200 in your checking account.
Westley: I mean, if we only had a copy of the Financial Times with the current exchange rates, that would be something.
Inigo: Where we did we put that copy of the Financial Times the albino had?
Fezzik: Over the albino, I think.
Westley: Well, why didn't you list that among our assets in the first place?

Not Really...

Step one: What is (are) the question(s)?

Where can Westley get a sword?
How much does the sword cost in dollars?
Is it affordable?

Step two: What do we know?

According to the Financial Times, $1.00 = £0.63.
The checking account has $200 in it.
BruteSquad.com has swords for £125.

Answer All of the Questions...

How much does it cost in dollars?

£125 x ($1.00/£0.63) = $X
£125 x ($1.00/£0.63) = $198.41

Is it affordable?

Yes, $198.41 is less than $200.00.

Where can Westley get it?


One quote that I used that I found unintentionally hilarious was this one from Robert Boyle on his experiments determining that the volume (extent) of a gas was inversely proportional to its pressure (spring):

'Tis evident, that as common Air when reduc'd to half Its wonted extent, obtained near about twice as forcible a Spring as it had before; so this thus- comprest Air being further thrust into half this narrow room, obtained thereby a Spring about as strong again as that It last had, and consequently four times as strong as that of the common Air. And there is no cause to doubt, that If we had been here furnisht with a greater quantity of Quicksilver and a very long Tube, we might by a further compression of the included Air have made It counter-balance 'the pressure' of a far taller and heavier Cylinder of Mercury.

Even in 1662, scientists were complaining about not having enough funding.

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dxmachina: (Default)

February 2016


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