I go off topic all the time; it’s how I teach. But I was miles away twice last week, and both may make interesting stories. I wrote about the first earlier. Here’s the second:

I’ve been doing math stuff in the Bronx for years. I taught, eventually gave a few talks, did a Saturday enrichment thing for a while, picked up the college gig, got involved with pre-service Teaching Fellows for a few years…

There was a pause. I might have been in trouble. They were thinking.

Sometimes things come together. I encouraged a neighbor, Numbers Guy, to become a math teacher. Huge personality, a natural. And last fall he was accepted to the Teaching Fellows. One of my math campers from a few years ago, Early Riser, rises from his school’s Siberia, the trailers, and step by step, out of teaching: he is now an AP. Numbers Guy was looking for a job. It took a little convincing, since Early Riser does middle school and Guy wanted high school, but it has worked, exceptionally well, as a matter of fact.

So Numbers Guy picks up math team. And invites me to come. And Early Riser thinks it’s a great idea. Plus, their school sends my school a few kids every year. And last week I did middle school math team. What to do? Numbers Guy was open to anything. This was going to be fun.

1. For a warm up, an old standby:

(in a very soft voice, and very fast… imagine an auctioneer whispering)

There was a pause. I might have been in trouble. They were thinking. I hear “6.” Oh no! Then a fraction of a second later “5,” then mostly 6s. Didn’t matter. We had our 5. I put up a fist, and counted “32, 33, 34, 35, 36” I swiveled my head, looking for the last finger, maybe I dropped it. Giggles. Brief discussion. Then I asked “if you walked from 32nd Street to 37th Street, how many blocks would that be?” Quick answers “6!” Brief discussion. I drew the silly fence, and discussed rail problems versus post problems, mentioned places later in the curriculum where the same or a related concept matters (endpoints) nad moved on. I had them.

2. Number guessing games. I told them that for a guessing game to be good, it had to impress and  seem mysterious, and it had to work.

A. Pick a natural number. Multiply by 10. Subtract 1. What do you have? And as the first few kids answered, I gave them their original numbers. Numbers Guy offered to guess one. And then I asked a kid to guess one. And we agreed that everyone in the room could quickly figure out the numbers. This was too easy; it failed to impress.

B. Write your birthday as a month (1 – 12) and a day (1 -31). Add one to the day, multiply by 20, add the month. And I correctly guessed 2 or 3 birthdays. And then a kid tried, and got one. And another. But some still were a bit puzzled. I had them help me symbolize it, and they all got each other’s birthdays. This is the sort of thing, I told them, that I get from friends, forwarding me e-mails. They want the explanation. For many people this would be a good guessing game, impressive and mysterious, but not for you anymore…

C. Take a number. Square it. Take the last digit. Square that. Take the last digit. Multiply by your original number. OK, now this was interesting. I agree that there is a weakness (there was a 10 and a 20, and I needed two guesses), but they are impressed. And I deny explanation. Try it with a bunch of numbers, 1 up until… by the time you get to 50 you will certainly know that multiple tricks that are in play. And then, to give myself a chance to recover (all high energy, middle school kids) I spoke briefly about Pierre Fermat. Turned out, the kiddies knew lots of pythagorean triples, and I sat back and let them recite a few.

3. The big puzzle. I was thinking Ghost the Bunny, but one kid said he knew a bunny problem (and lo and behold, it was just a simple explanation of the Fibonnaciness of bunny multiplication), and I was also thinking the Logical Pirates, so I put it to a vote, Bunnies or Pirates, and having rigged the question, I knew we were going for the pirates. (this means, of course, that I must post the Pirates problem, soon). I ran a good session. I let them make mistakes. Slowly correct themselves. I asked annoying questions (that seems possible. Are you sure that it shouldn’t be one more? how do you know that that’s enough?). The Numbers Guy helped with the questions (even as he did not know the answer). And the Early Riser came in and out and watched a bit. He solved the Pirates with me years ago.

And we had a solution. Then a refinement. Then an extension, which we noticed changed the nature of the problem. And then I turned to the Numbers Guy and said I really wasn’t ready to go on. Perfect, he answered. I was confused for a moment, then saw the clock. I’d been there for an hour and a half.

January 19, 2009 pm31 10:11 pm 10:11 pm

That does sound really fun! I think I’d enjoy that a lot more and I’d learn a LOT too!

• January 20, 2009 am31 9:56 am 9:56 am

Once upon a time Bronx teachers used to run their own Election Day pd. I once did a presentation on problem solving. Other people gave talks from their strengths. There were enough going on each session that we each got to pick what to see. Much better than most of the useless stuff that masquerades as pd today. And yeah, I might have put on a show for any math teacher in the Bronx who wanted to watch.

2. January 20, 2009 am31 12:35 am 12:35 am

Impressive! That sounds exhausting. Memorable all around, though.

3. January 20, 2009 am31 7:51 am 7:51 am

When I was a brand new teacher I begged not to have freshmen. And eventually, I didn’t.

My control got better and better. I gained confidence. I asked for freshmen coverages (for an absent teacher, in a huge school where most kids wouldn’t know me. Awful for control issues). And I would walk in, and that counting bit was my shtick.

Preamble was longer: No work for you today. [pause, I’m looking earnest], I just need to take attendance, and I don’t want to ruin your free period, so just bring up your ids and I’ll deal with the paperwork (grumbles, and the kids who didn’t belong but wanted to hang out in the sub’s room, slipped out). (IDs come up). Thank you. You have a free period. The department didn’t have work for you, and I teach math, not (fill in the blank) ________, so I couldn’t give you work even if I wanted to. Anyhow, you all already have you math courses, right? (pause). Let me just make sure of that, we’re not doing work, I just want to make sure all of you actually have math. (hands up, yells of yes, yes). OK, ok, free period. (one beat). But just to be sure, you all have the right background. Did all of you have mathematics in middle school? (yes yes yes) Good. Free period. But hang on, did all of you get taught fractions, back in elementary school? Even if you didn’t get them, at least someone tried to teach you in 4th grade or so, right? (yes yes! !) Good good. But. Before that, times tables, and additions? All of you learned them? I just want to make sure. Remember, this is a free period. (yes yes – impatiently now). That’s great. We’re all set. You’re all taking math. All of you have had math up to now. You’ve seen fractions, times tables…But, before that, in kindergarten, or at home, you learned the most basic math, right, you learned how to count?

And then I would launch into #1, above. The loudest, fastest answer was always wrong, and I would keep them going for an entire period.

I was, honestly, entertaining myself.

4. January 22, 2009 pm31 9:29 pm 9:29 pm

good stuff! counting counts! keep ’em coming!