I would want to make sure my students understood the following three things about being good digital citizens:
1) We're not just keeping them safe from bad stuff online, but safety to empower them to do good. In other words, it's safety for a purpose.
2) It's important to be introspective as digital citizens. Ask yourself questions about the purpose and tone of your communication-- will this offend others online? Check your tone, grammar, and spelling to make sure you really mean what you've written.
3) The Internet is forever! Oftentimes, it is very difficult to remove digital information you've posted. So if the things you're posting are things you wouldn't want your own parents, someone else's parents, the police, or a college admissions director to see, you probably shouldn't be posting it.
I plan to use the Brain Pop video from the Ed Tech website. It's short, to-the-point, and can stimulate some great discussion. Also, the tone of it is less threatening than some videos/presentations, and would make students feel more empowered to protect themselves rather than tempted to break a set of rules. I would use the resources from the EdTech website to help teach the idea of digital citizenship to my students, and I would also maybe show them some examples of bad digital citizens. Parents can take an active role in digital citizenship when I invite them to see presentations or projects their students have created online, and to respond to posts on my class blog or class Twitter.