Short post today since I’ve miles to go …

Talked about the idea of a rate: the amount you pay for gas depends on the amount you buy, but the rate at which you pay, the number in dollars/gallon posted at the pump, doesn’t change. If inflation from year A to year B is 6%, then 1 year A dollar can buy what 1.06 year B dollars buys. 100 year A dollars are equivalent to 106 year B dollars. The amounts differ. But the inflation rate is 6% in both cases.

I need to write a section in the book about this. But how many students actually read the book? I didn’t dare ask in class.

We had fun (at least I had fun) converting gas prices in euros/liter to dollars/gallon. Tried to convey the idea that the reality was the same – expressed in a different vocabulary. (For what it’s worth pedagogically, I’m about to have to teach the same idea in linear algebra, where vectors correspond to different n-tuples depending on which basis you’re using.)

Talked a little about the metric system, for everyday quantities. Did kilo=1000. More next week, then the exam.

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