Yes, you can trust the class

I just finished my first lecture of the year, and I'm relieved to say that it went even better than I'd hoped. This was the first day of intro physics, so most of it was general big picture physics stuff: how physics shows up in everyday life, how it fits in with the other sciences, how the field as a whole fits together. (There was a bit of administrivia, too, but I tried to minimize that for the first day.) I probably rambled a bit, but that's par for the course for me.

But I had planned a small group activity for the very end of class that had me a little nervous. To introduce the idea of physical models, I did a brief little slide show answering the question "What shape is the Earth?" It's a sphere, of course, but that model seems laughably wrong when you're standing beneath a mountain [I used my own photo here]. And from far away in space, the Earth just looks like a point. The group activity at the end was to have the groups try to come up with other models of the Earth that might be useful in different circumstances.

My worry was that it's hard to come up with meaningful ideas on the spur of the moment (and there really wasn't a lot of time left for this at the end of class: five minutes or so). In fact, I had only come up with a couple of ideas myself ("flat", which is pretty darn good in everyday life, and "ellipsoid", which is the first correction to the basic "sphere" answer), and a student had already mentioned "elliptical" during the slide show. But as I said above, yes, you can trust the class. I think every group probably came up with "flat" (certainly the one group I called on at random did), but I also got "interlocking tectonic plates", "fractal", and "slices" (that last one being a great way to visualize the whole internal structure of the planet). That bodes well for the rest of the semester.

[And now, time to finish preparing a colloquium for Cal State Northridge this afternoon. Busy day.]