3) So I did this:
There is a post-script:
There is a second, even cooler part of this activity - balancing a cinderblock on my chest while lying on the bed of nails and having an assistant break it with a hammer. I was really excited about doing this, but my Principal was really, really uncomfortable with the idea.
I pushed very hard to be allowed to do it in front of my classes, which is my job.
He was cautious and responsible and looked at the big picture, which is his job.
Ultimately, I wasn't allowed to do the breaking-the-cinderblock-thing with my class, so I did it after school with a couple of colleagues.
It was even better than I had imagined!
I feel really happy and gratified by the back-and-forth that my Principal and I had over this; we both did our jobs passionately and well, and yes, I do understand that from a liability and a setting-a-good-example, and from a common-sense point of view, this whole exercise is not terribly defendable, so I don't expect to ever be allowed to do it again, but Educational Awesomeness doesn't happen every day and I'm really glad I was there this time when it did.