I've been writing a series of online text and image tutorials for my students using Google Docs, and publishing them as websites (File -> Publish to Web, it's really easy). I really like this method because making changes is as easy as opening the document and editing it. Since it's Google Docs, I don't have to use any fancy code, and formatting is really simple because it's like any other rich text editor. I've tried using videos, but they take so long to record just right and get up, and if you need to make changes you basically have to start from scratch. I've also used blog-posts (too hard to format and edit), Google Classroom (doesn't seem very permanent, and limited formatting options), and other third party apps. How often do you guys write guides for your students? How well do your students take to them?