Working with technology in a middle school setting, I have had many opportunities to have great discussions with students around the school's tech policies and general guidelines for safe and responsible computer use. These moments come from formalized lessons and projects from our WHAM sessions in advisory or our attempts to engage students in a wider discussion via the Digiteen Project. They also arise in the small day to day interactions with students about topics such as gaming, appropriate taking/posting of pictures, blog and forum etiquette, appropriate use of bandwidth and the school network, file management, passwords and security, and physical health.
I make an effort to model these types of behaviors for students in the way I communicate with them via email, the way I post comments on public forums, the way I protect my privacy on social networks, the choices I make about pirating and copyright, etc. These tend to be the most valuable learning experiences for students when they can question me about my computer use and I am able to give them responses that support the goals of the school's policy as well as general realities of life on the internet.