Guernsey's Education Department has urged parents to make sure their children are using social networking websites safely and wisely.
Alun Williams, lifelong learning manager for the Education Department, was responding to findings in the latest young people's survey.
The survey found that two thirds of primary-school age children use social networking sites such as Facebook.
It also found that girls are not exercising enough as they get older.
Mr Williams oversaw the survey and said the exercise trend was worrying.
He said: "The drop off in enjoyment and participation as people get older is an area for concern, especially among girls.
"We are concerned that as they hit their teens we don't engage them in the right kind of activity.
"That is work we want to do as an outcome of this survey, to analyse that and think about what we can do more."