It replicates some of the aspects of youngters living unsupervised, bringing some of the themes of the book more obviously to life. This happens most clearly when you try to look at the story through a thematic lens of human nature--what people are like in difficult circumstances.
It's satisfying when you see confirmed before you your expectations of which students will hum along just fine without any real supervision...about as much as it is strangely compelling when those students you think will completely exploit the system and do absolutely nothing confirm your worst fears.
I admit, it's also pleasantly affirming when the student chief stands before the class and explains his/her frustrations with what the students are doing. We've heard more than one, "I have a new found respect for the teachers."
And then sometimes it's just fun. Today, one class had a sit-in protest. (We just did a unit on civil rights, and I think they got the idea from that.) They succeeded in removing their interim chief (the regular chief is absent) for the remaining 9 minutes of the period.