Had a frustrating day introducing 2-point perspective, but I was actually quite surprised at what seemed to be tripping some of these students up. It's a pretty simple concept -- at least I think it is -- but I thought it might be a good idea to put the relevant info together either to make a handout (which I think promotes intellectual laziness) or a web resource of some sort (which may still inspire some students to be less mentally disciplined, but may save me from explaining the same concept weeks after it was initially introduced).
If this proves useful I might end up doing my whole curriculum in this manner and start a site or blog just to host it as a resource.
So, here's my primer on rectangles and diagonals in perspective.
The code for this entry got horribly messed up as I uploaded some corrections so I deleted the previous version and just put it up as a new entry -- sorry about the lost comments as a result.
Also, I seemed to have glossed over it in the original: this isn't a full perspective lesson by any means and much of the above info could be quite confusing to anyone not aware of the terminology and set up I'm using with my students.