This is a good question - how to approach assignments, I think I am probably thinking in terms of young kids, and working together. Sleeping overnight might need more input from the kids. Older kids I guess this figures in more. I googled on this idea, there seem to be some articles on partnering in the classroom, this was a good one:
http://www.proteacher.org/c/988_Choosing_Partners.html

And I found some articles on doing profiles for students or team mates who would room together longer term, but I really couldn't find anything for short overnight stays/younger kids...

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