One in five children aged nine to 11 admit meeting up with strangers they speak with online, according to a survey.
In half these cases, the children went alone, found the study conducted by ISC2, a technology security group.
The research results, released on the first day of Get Safe Online week, were taken from a survey of 1,162 pupils, of which 18% admitted they felt uncomfortable or upset chatting online to a stranger.
Tim Wilson, the member of ISC2's safe and secure online programme who conducted the survey, said: "Young children seem to approach the real world and the virtual world very differently, and as a result, their perception of safety is skewed when spending time online."
This is not helped, he suggests, by a total of 15% of the interviewed children claiming their parents do not check their online habits, with more than a third accessing the internet from their bedrooms, with 32% saying they were two to six years older than their actual age.
One in five also use the internet after 10pm, and 7% after 12am, with more than 30% of the schoolchildren admitting they were tired in class the next day.
Nearly half of children have shopped online, and 42% said they have used a webcam, with 6% posting a picture of themselves they would not want their family to see.
"For parents, there is a strong call to action to ensure they are engaged in how their children use the Internet," Wilson said.
"Bringing the family computer into the living room and having open conversations about potential online dangers will help them play a more active role in the relationships children are increasingly starting online.
"Parents should ensure their child is comfortable enough to discuss seeing something they shouldn't online. For teachers and schools, the results point to an urgent need for more education on Internet safety to pupils, staff, and parents, especially with Ofsted monitoring pupil attendance and lateness."