Today there has been a BEM workshop in our company (SC5 Online, Helsinki, http://sc5.io/) We studied basics like CSS approach and modular file structure. People did their tasks one by one "at the stage" :-) These are the slides, and the task is inside http://varya.me/bem-css-workshop/
Finishing the tasks we could compare the changes we provided without BEM in mind https://github.com/varya/bem-css-workshop-source/pull/1/files and with BEM https://github.com/varya/bem-css-workshop-source/pull/2/files In my mind, it shows the different very clearly and it is easier to understand the idea of BEM. Even better than presentations and the articles.
BTW, I was surprised to learn that many don't know about BEM selectors supporting in SASS and LESS although this is at least 1-year-old feature.
How is it in your mind? Feel free to use slides.