The Blue Pen Code

18 May 2010

On the first class day of any semester, there are some things that happen no matter what course I happen to be teaching.  Like most teachers, I have a certain spiel; some of it changes and evolves, but some of it stays pretty constant. Here’s one of my “greatest hits”.

You have to understand what I see when I’m up here talking and looking out at you. Most of the time in a typical math class, there’s just a sea of dozens of dead faces. And that’s bad, here’s why.

I try to be responsive to all of you. If you’re all bored, then I need to be speeding up. If you’re all lost, then I need to be slowing down. But here’s the thing: lost face and bored face are identical. So if you’re confused, if you want me to clear something up, if there’s something you think we should talk about as a class, I need you to let me know. Otherwise, I’ll probably respond by doing exactly the opposite of what you need. Not to punish you, just because I can only respond to the cues you actually give me.

And folks, I understand if you’re embarrassed. But this something that you need to find a way to do.  I once had a student who sent me an email that said, ‘I’m too nervous to ask questions in class; so between you and me, when I hold up my blue pen, that means I’m in trouble — help!

In the business, it’s what they call a “laugh line”.  And as laugh lines go it’s a good one; they always laugh.

So if anyone needs to set up a ‘blue pen code’, just email me and we’ll work something out.

More laughter.

And it’s the damnedest thing, but in every class, every term, I get a person or two who takes me up on it.

Read the rest of this entry »


NAA: The Monty Hall Problem

17 May 2010

Today at Not About Apples, I give my take on what might be the most confusing and misunderstood (certainly the most fistfight-inducing) probability question in history: the Monty Hall problem.

As I tell it, this is the story of the following scripted game. The characters are Alice (the contestant) and Hatter (the host).

Monty Hall Setup

There are three doors.  One leads to a car, and the other two lead to goats.  (The locations of the car and the goats are assigned at random in advance, and Hatter is aware of what is where.)

Alice chooses one door (which she hopes leads to the car) but does not open it.

Hatter, knowing where the car is, opens one of the doors that Alice did not choose, showing her a goat.  (That is, if she picked a goat, he’ll show her the other goat; if she picked the car, he’ll arbitrarily choose a goat to show her.)

Now there are two doors, and Alice knows for sure that one leads to a car and one leads to a goat.  Hatter then offers Alice the option to either switch her choice to the other door or stick with the door she had chosen at the start.

Assuming that Alice wants a car and doesn’t want a goat, is it in her interest to take the prize behind her original door, or is it in her interest to take the prize behind the other door, or does it not matter?

Permalink: Cap takes on the Monty Hall Problem

Breaking the Hiatus

17 May 2010

Ow! My hiatus! I think it’s broken!

But seriously, it’s been a long time since I’ve pulled out my trusty text editor and updated my blogs. The time-management problem for a post-doc, especially one with a family, is insoluble. I’ve let my blogs drop for some months because I felt that would have less bad consequences than neglecting my research or neglecting my children. It’s not something I’m proud of or happy about. But I’m back, and hopefully to stay for a while.

I’m not going to waste many keystrokes on handwringing and mea-culpa-ing. That’s not, I assume, why you’re here. (If anyone did come here specifically for an apology, if anyone feels personally wronged by my hiatus, by all means please contact me for a personal apology.) Instead, I’m going to hit you all scatter-shot with some blurbs about what’s going on in my life, in my head, and in my browser.

  1. On Mother’s Day weekend, I attended the Michigan sectional meeting of the MAA and Math-MATYC. I gave a talk on Apollonian circles which was pretty well-recieved, saw a variety of talks, many interesting but none quite so implausible as the one by the mathematician/Marcel-Marceau-trained-mime on the connections between math and mime, met a lot of amazing people, and caught up with some old friends. Congratulations to John Fink of Kalamazoo, incoming chair of the Michigan Section of the MAA. Congratulations also to Ruth Favro, who received a spectacularly-deserved award for distinguished service.
  2. Gabriel likes spending time playing at the Wii with his daddy. (He sits in my lap; sometimes he gets his own controller, sometimes we share one.) Sometimes he brings me or Susie controllers if we haven’t been playing enough. His favorite games: Marvel: Ultimate Alliance (if I set it on easy, he can actually walk his guy around with mine, and I can fight things while he fires off powers at random and laughs), Strong Bad’s TCG4AP, pinball.
  3. Speaking of pinball, since my last post they put a new Starship Troopers pinball table at the Fenton House. I had never tried that one before (it’s one of the new-generation, lots of bells, whistles, and gimmicks). Only played it three or four times, but my impressions are positive. The third flipper increases the challenge a lot more than I’d have thought possible.
  4. The spring semi-semester is in full swing, and I’m teaching Intro Probability (Math 425). These spring/summer math classes are brutally paced. A semester’s worth of math in seven weeks. And there are always people who take the classes in the spring/summer then because they think it’s going to be easy.
  5. The recent Betty White census sketch gives me an excuse to mention, in case some of you haven’t seen it, the original Christopher Walken census sketch.  Everything’s better with Christopher Walken.
  6. Have nostalgia for the days of the NES? Then you really need to try out Super Mario Crossover; you can play through the levels of the original Super Mario Bros. as Mario, Link, Samus (from Metroid), Simon (from Castlevania), the Contra guy, and Mega Man.
  7. Have a grudge against the days of the NES? Then maybe you should try out Pixel Basher. Not too hard (in fact, quite easy if you don’t care about getting the 6th achievement), but a fun way to spend a lunch break.
  8. Iron Man 2 was a lot of fun (most of the fun was had by Gabriel, who was actually doubled over with laughing so hard). I got him to say “Iron Man!”, and to make a valiant effort at “War Machine” and “Whiplash”, but the “sh” sounds are chaIllenging.  Interestingly, he seemed most totally fascinated by Tony Stark in his lab, doing scientific stuff.  Maybe he’s a future scientist.
  9. In case you missed the April 2nd episode of On the Media, this story by Adam Davidson of Planet Money is a really useful perspective on media coverage of complex events in general and the economic crisis in particular.  The takeaway: it is not informative to give people the false impression that they understand something.
  10. I’ve discovered that I really like Bob Seger; I picked up a greatest-hits album for my birthday. I wonder if I like his music so much because it reminds me of the music they play at Pinball Pete’s.  I only really listen in the background, because pinball takes concentration, but I have a lot of vague-ish memories of Bob Seger, Queen, and ZZ Top.


Is anyone reading this? If you are, what would you like to appear in this space? My time is scarce, and I know I’ll never find the time to post to my blog all the things I think of to put here. So what should I prioritize, dear readers? Vignettes of my personal and family life? My thoughts on teaching? Recommended links? Cookie recipes?