Help me remember a story

I remember reading a personal account some years ago, about someone’s high school principal (or some other staff member) coming into a classroom and reciting the relative worth of various groups of people, as a kind of protest against apathy. It was something like 10 million famine-struck Tanzanians equals a hundred thousand Indonesians killed in a flood equals 200 Americans killed in an earthquake equals one guy from your neighbourhood killed in a car crash. I seem to remember it being a fairly widely-circulated story (an email forward, perhaps), but I don’t remember the exact wording enough to google it. Does anyone else remember this?

The Monkey Sphere.

Also known as Dunbar’s number.

Well, I guess that’s the general idea, but I mean the story was actually about the principal coming into the classroom and so on. Anyone remember something like that?