Its not that complicated. When boundaries are drawn they try to include at least a few disadvantaged neighborhoods for each school so the test scores won't be out of wack.

For some high schools the boundary line for another school come right up to a few streets from the first school. Look at Wootton's lines. They go all the way up Route 28 and if it wasn't for the trees kids who go to Wootton could see Quince Orchard.

On the other hand Quince Orchard's boundary lines go way east on Muddy Branch Road, at least five miles from the school, and people who attend QO can see Gaithersburg H.S. from their apartments.

Just about every high school has this gerrymandering except for Whitman that does not have a disadvantaged area unless you want to include the few houses left on Carver Rd. Even Churchill has an area (Scotland0 that helps to lower their scores a bit.

Arlington co. currently has an interesting boundary tool on their website: http://reingoldweb.com/arlington/online-boundary-tool5.html
It allows you to play around with the planning units in the northernmost, overcrowded part of the county to redistribute them evenly across existing schools and a planned new school. It can give you an idea of how you can end up with really funky boundaries. How they decide on planning units I don't know, but those are the smallest neighborhood units and aren't supposed to be broken down further.

I would also love to hear answers to this questions. Also, how often are the boundaries moved (if ever)?

I was just looking at the MoCo school boundary maps, and was amazed at the Gerrymandering. They curve in an out of neighborhoods with no discernible pattern. Does anyone know how do they get drawn and/or changed? I'm assuming there's some sort of political element, where different neighborhoods lobby to be attached to particular schools, but it seems like there would always be other neighborhoods lobbying the other direction.

Does anyone know how it works?