Virginia has become the first US state to mandate internet safety classes for children.
Texas and Illinois already have laws on the books for similar lessons but Virginia is the first to make the lessons mandatory.
The move follows increasing fears that paedophiles are using the internet to prey on younger users.
Virginia assistant attorney general Gene Fishel launched the initiative with a series of classroom lectures at the James River High School.
Children were shown a social networking profile of 'hotlilflgirl', who claimed to be 15, enjoyed being with boys and wanted to meet new people.
Fishel then showed them who actually posted the profile: a 31 year-old man convicted of sexually abusing 11 children he met online and who is now in prison. "Not little, not fly and not a girl," he said.
Parents were also warned to look out for the warning signs, and to make sure that the message is getting through.
James River High School student Maya Towers said: "I thought it was very important because we post a lot of things on the internet. I didn't know how much information can be exposed."
