overbooking & orders of magnitude

Every morning I give the kids a five minute warning to get in the car. Yet many mornings I end up waiting for one of them. On Friday, as I was waiting for A, I thought I would start telling them to be ready five minutes before we would actually leave so that hopefully by the time I got to the car they would all be there. I mentioned this to them and told them about overbooking by airlines. They were not familiar with this "practice" of selling more seats than are available with the expectation that some people won't show up. We also spoke a bit about the capacity of commercial jets: some guessed 100 other 1000.

This reminds me that the other day I spoke to them about "orders of magnitude". I had a chemistry professor in college who would tell us that all he wanted us to know were the order of magnitude of the responses. It was OK if we answered 40 when the actual number was 60, but not if we answered 50 when the answer was 5 or 500. This is obviously of particular relevance in chemistry where you talk about the size of atoms and molecules, and the time it takes for physical reactions to take place. Most people, me included, can't guess (or remember) the right order of magnitude for the size of a molecule... Can you? But this applies as well to more day-to-day topics, such as the size of an airplane...