Joe the Box is a delightful introduction to programming in Morphic that was put together by Joe the Box. The idea is that you start with a concrete object, Joe, which shows up as a rectangle on your screen. You learn aboun programming in Smalltalk by sending messages to joe and watching him react. As it progresses, you can use more and more complex messages, you can create "jane" which is an element of the same class, and you can add methods to the class.
There is a morphic version of this in modern Squeak, and this page should link to it...
Also, did Mark Guzdial use it in his Squeak book? I can't remember. - Yes he did! Chapter 3 of Object-Oriented Design with Multimedia Applications (available online for free).
