What teachers need to make sure students know. Do not 'assume' they already know it.
Know the difference between personal and private information.
Go beyond Internet Safety
Example: Keep it Private
Very simple rules for young kids, but take a look at the lessons as you get to middle school
Older students should be able check their understanding through peer discussion. Here is a good presentation[ get_fileinternet.pdf ] by Karl Hopwood which can be used with that age group.
Downloadable Poster from Edmodo - Best Practices for Digital Citizenship
Some schools ask students NOT to use their real name. If you need to help students create avatars, here are a few sites. Yes, there are other sites, but these are both fun and safe, and quick as time is precious!
Build your Wild Self
New York Zoos and Aquarium let you create a 'person' with animal parts.
Create an avatar from facial parts and expressions. Good for the slightly older student.
Create a cartoon character.
Build a clay model of yourself.