Physical Activity for Objects I have a vague notion that I could create some sort of introductory activity for Objects.  There would be worksheets ("programs") to get kids (high school, in this case) to physically go through the process of isolating behavioral groupings into different people, and using message passing to solve a problem or accomplish an algorithm, but I don't have a great idea for one to actually implement.

It would be a bonus if it wasn't immediately apparent what problem the students were solving at first, but the final output created a nice "A-ha!" moment.  This would allow us to talk about the benefits of dividing a problem into component/machines instead of merely into sub-functions.

Has anyone done something like this?  Or does anyone have an idea for a fun, physical activity to introduce some core OOP notions?
If the objects are something like robots or other things that "move", like froggies, or such, then you can do things like maze solving and other interesting things. If they can move some sort of other objects by picking them up and putting them down in piles, then you can sort and such. Of course they need some sensory behavior to sense boundaries. 

There are a number of scenarios available for Greenfoot for example that permit this sort of thing, either with a Java program or with student "actors". 

The left hand rule for walking a connected maze is kind of fun. And there are actually sorting routines for physical objects that are unlike the usual algorithms. 

But it is moving under some constraint that makes it work. 

Find the resources at the Greenroom for ideas. I think the first scenario in Greenfoot involved Wombats, but the developers were then in Australia. 

Alternatively, you can have the students simulate a cpu that executes the program, moving some objects on a game board. The hard part of this, however, is capturing the message passing idea of OO. That is a bit easier if the students are, themselves, objects, since speaking/asking is a lot like message passing.