Tom Wujec gave an interesting TED talk about training people in team-work and engineering through building the tallest possible structures from 20 pieces of spaghetti, 1 yard of string, and 1 yard of sticky-tape with a time limit of 18 minutes . The project is completed by groups of four people – which is probably about the maximum number of hands that you could have on such a small structure at one time. They have a web site MarshmallowChallenge.com/ which gives some suggestions for conducting a challenge.
One interesting point made in the talk is that kindergarten students tend to do better than most adults.
I think it would be good to have such challenges at events such as Linux conferences. The type of people who attend such conferences tend to enjoy such challenges, and it may lead to some lessons in team-work that can help the software development process. Also we can discover whether Linux programmers are better than the typical kindergarten students. ;)