GotToBTru,
The idea was to - at the end, ask them "what if we weren't sorting based on height, what if we were sorting based on age or name - would it still work"? To get them to explore the idea of re-usable algorithms. I get the whole height thing being self-concious. Instead, what I would likely do is have them hold a sign with a number on it. I plan on doing the "make a sandwich" experiment as my first option but fall back to this if there are any severe nut allergies.