Lecture
We're going to learn the basics by implementing this: http://littlesvr.ca/processing/squarespiral.html
If you look at the code you may think this is so simple it's not worth your time, but this is a first implementation in a library you haven't used before, possibly in a language you haven't used much, so there's a lot to learn by implementing it.
Links
Lab
You will modify and extend my first example.