Class 2 – Thursday January 26, 2012

Plan: Last time we did two Fermi problems – with no formal instruction at all about what they were, or about curly arithmetic. I asked them to look at the homework problems from the book (due next Tuesday) before coming to class today. When I looked at them last night, and prepared answers for the two that had never been assigned, I realized how much of a stretch it will be for them even to begin, let alone know how to write a solution.

I think I will use the class today to do one or two of the problems – perhaps model a solution for the whole class, then break into two or three groups to try another. The homework can still call for writing up the solutions to the problems done in class as well as working out the ones we don’t

I think I will connect the computer today, show them the google calculator and use the web as appropriate – but not too soon. Maybe let them drive, in turn.

It is a great luxury to have a small class in which almost all the students seem to be alive and awake and (at least potentially) actually interested.

What really happened:

Class size seems to be up to 9 or 10. Still intimate.

We worked “have you been alive for … seconds” collectively. Starting with an opinion survey on the order of magnitude. Then we estimated, using curly arithmetic (there are 60*60 ~ 400 seconds in a day). Then we asked the Google calculator for 20 years in seconds to confirm the order of magnitude.

I left the connection to heartbeats as an exercise.

I told the class that I’d lost some sleep last night working on a math problem, which they wanted to hear about, so I took ten minutes to write down the Thue-Morse sequence and explain its relevance to equalizing the strength of two cups of coffee. Then I wrote down the ternary sequence I’m trying to understand, hoping it will solve the three cup problem.

We spent the last 15 minutes in small groups, working independently on the size of the tooth fairy economy.

I hope I gave them enough of an indication about how to approach Fermi problems (which don’t have “exact answers”) and how much to write as a solution. I just have to remember that it’s only the second day of classes and that with feedback from the first assignment they’ll learn a lot more.


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