Guy had a great story from his newly started Technical Writing class:

The professor started class, announcing that Technical Writing was largely a collaborative class.
If anyone had problems in high school or college with collaborative efforts because they did all the work, please raise your hand.
A bunch of kids raise their hands.
Great, you're going to be the team leaders for each of our teams. Come on up to the front of the class, and line up facing the rest of the class. Good. Now, each of you, tell us your name, major, and what interests you.
Each of the type-A kids give their spiel.
Now, if you have a preference about whose team you'd like to be on, come on up and stand with your team leader.
Some kids file up, while others just sit.
If you don't have a preference, join any team that evens out the number of people per team.
Apparently, the teams balanced fairly well.

How often would the teams balance well ( n = number of members in smallest team, and no team has more than 2n team members )? Why?