By Ben Geoghegan
Computers are now integral to schooling
Pupils are using special websites to hack out of their school computer network while in the classroom. They then access social networking sites and even hardcore pornography.
On one school's computer it was enough to type the word "naughty" into the internet browser and hit return.
Another click on the images tab and there appeared a whole page of pornographic thumbnails.
Most parents would agree that sort of thing should not happen.
So what does it say about internet safety in the classroom?
More than 85% of pupils now have access to the internet at school; on average, in secondaries, there is one computer for every 3.6 children.
They are integral to modern education but they also provide opportunities for "cyber slacking" or worse.
Computers installed in schools usually come with an internet filter which is supposed to select out the dodgy stuff leaving children free to surf safely on the web.
Some children know how to get around their school's system
The fact is though that some internet filters are better than others and they can be by-passed.
I met children who said they could easily hack out of their school network using so-called proxy avoidance sites. Once outside they surf where they like.
One recent piece of research by the software company Zentek produced some alarming figures.
They monitored internet use in around 70 schools and found that in some, pupils were accessing up to 4,000 "unauthorised" pages a day.
In most cases they were going to social networking sites such as Facebook or Myspace. But they were also encountering more harmful material, such as porn and violent video games. Some were sending abusive messages to fellow pupils.
Zentek's managing director, e-safe education, Colin McKeown, says: "We're not out to demonise children.
"Ninety per cent are absolutely fine when they use the internet. They are generally good but they bump into things on the web, just as they do in everyday life."
The psychologist Tanya Byron said when she published her review into children and new technology last year that there was "room for improvement" when it came to internet safety at school.
The chairman of the National Governors' Association, Phil Revell, points out that a lot of schools are doing great work in installing better filters and teaching children and staff about using the internet safely.
But he adds, "in some schools I think people are complacent and they're complacent in the same way adults and parents are complacent".
"They do not imagine that their children are actually going to these unsafe areas. I think that's a naive view of young people."
The government says this is something which the new UK Council for Child Internet Safety will look into.
But perhaps it raises a more worrying question: if children are accessing harmful sites at school, then what are they doing at home in the privacy of their own bedrooms?