More children are being locked up in England and Wales than any other country in western Europe.
There are 3,000 under-18s currently incarcerated, compared to Finland's four, and the trend has been steadily increasing over the last 15 years.
Until 1995, courts could only send a child into custody if they'd committed a serious crime such as rape, murder or GBH.
The number of children being sent to prison for those types of crime has dropped since then but thousands more are being locked up for minor crimes.
Labour's Tough On Crime policy also makes it much easier to give younger people a custodial sentence for things like breaching community orders or breaking a curfew.
Former young offender Dave is now in a support programme.
He said: "I think jail's pointless for petty offences like what I've done or what a lot of young people do."
So is jail really the right solution for offenders aged under 18?
A recent poll from children's charity Barnardo's shows that society holds a negative view of young people, with 54% of the population believing that British children are beginning to behave like animals.
49% also disagree with the statement that children who get into trouble are misunderstood and in need of professional help.
Feltham Young Offenders Institute houses 764 inmates
John Anthony from the Youth Justice Board, the body which oversees the youth justice system in England and Wales, thinks there's a problem with the way we think about young people.
He said: "As a society we have a role to play in how we portray young people.
"If you're making decisions in the context of hoodies, thugs or that youth are out of control, it's very hard to have a discourse about therapeutic interventions."
More than half of the children in custody have lived in care or had previous involvement with social services.
Nearly a third have a recognised mental health need and almost all of them have been excluded from school.
Andrew Neilson, from the Howard League for Penal Reform, thinks the UK's state system fails disadvantaged children.
He said: "If a young person is committing crime, they're not just evil out of the blue. They're troubled children and they have been victims.
"It's not about crime in that sense. It's about the way the government deals with difficult young people that it would rather not deal with.
"It shuts them away and forgets about them."
Minister of State for Justice David Hanson says the government needs to intervene at a younger age.
He said: "I do believe there is a role for prison for young people in society today."
Once inside jail there is often little time to turn young peoples' lives around.
Jerome, who's serving time in Feltham Young Offenders Institute, also thinks more experienced criminals teach newer inmates bad habits: "It ain't hard to ride jail, it's a piece of cake. It's just boring.
"Most people that come in jail, all it does it makes them wiser.
"They learn skills. They learn how to do things in a different way."
But Russ Trent, one of the governors at Feltham, says they provide activities to inmates to stop that kind of boredom setting in.
Ex-offender Danny is on a work based scheme called Youth Build
He said: "There is an opt-in for education or vocational training. We have prisoners under the minimum schooling age and those prisoners are very strongly encouraged to attend education."
But he does think offenders need to spend more time inside so they can get more help.
Russ Trent said: "In an ideal world Feltham would work more efficiently and more effectively if the prisoners were here for a longer period of time.
"I think what we can do is really have close contact with our prisoners to make sure that they do understand that they have got other options and to make sure that if they are willing to step onto the road of reducing re-offending, that we've given them every opportunity to do so."
Reoffending rates for young people sent to prison are high.
90% of children leaving custody will be reconvicted within two years.
A greater proportion will offend and not get caught.
Minister of State David Hanson said: "We need to improve our system to stop people reoffending.
"I've got very strong targets now to make it better for the future and I'll have to be held to that."
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