In the days of chat rooms, I had my two kids (10 and 14 at the time) watch me log in as an 18 year old blonde UK girl and witness the ensuing barrage of questions 'ASL' etc.
This taught them very quickly that not everybody might be who they would have you believe they are on the internet.
I'm pleased/proud to say they both learned well and I have had no problems with them surfing the internet.
I do appear in their respective doorways on occasion just to be sure though
