There's Jody Culkin's "Introduction to Arduino" comic as well: http://www.jodyculkin.com/comics-2/introduction-to-arduino

A friend & I used this as a teaching resource for the first part of a 3 hour workshop for non-programmers getting started with Arduino. We found it to be a great teaching resource (although I'm not a teacher and haven't tried any other methods, so I have nothing to compare it to.)