Over 1,000 children aged 16 and under are locked up in the UK.
Newsround Extra went into a secure unit to find out more about life for children who are behind bars.
Did you see the programme? What do you think of how children are treated? What should be done to help them?
Do you think imprisoning children is a good way of punishing them?
What ever your thoughts, e-mail and let us know.
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I think it is right to send bad kids to jail because they will learn from their mistakes and it also depends on what type of crime. If it is just for vandalising then it is sad.
Sam, 14, Wales
I think it's just pathetic 'coz some kids haven't done anything and even if they have they shouldn't get locked up until they are at least 17 and if they're not they should just get a warning.
Danni, 13, Rhyl
I agree and if you do a crime you should be punished. I think children should be put in a proper prison but for children not adults. I think life sentences are a bit harsh though.
Sarah, 14, Scotter
If you do the crime, you should pay the time.
Sarah, 14, Gainsborough
I believe that punishments are not strong enough as people continue to commit crimes after they have been punished. If there was a stronger punishment people will learn their lesson and think twice before commiting another crime.
Abi, 14, Lincoln
I think that children should be put in prison but only for a short while to make them realise what they have done, but if they offend again, a longer sentence or more serious action should be taken.
Charlotte, 14, Lincoln
I think sending kids to jail is a good idea because they will learn their lesson.
Georgia, 10, Munich
I think that depending on how bad the crime or how badly the victim is effected, the criminal should be isolated from the usual activities that they enjoy.
Annie, 14, Lincoln
Other kids will think it is cool to be locked up in jail so I think they will want to get locked up too. Which is stupid because it will mess up their jobs later on in life.
Daniel, 14, Scunthorpe
I don't have an opinion on this. For children, people feel sorry for them, even though they have done bad to be put in jail. As for adults, if they did the same things, people would say they deserved to be put in jail.
Nosheen, 12, London
I think if you have committed a really serious crime then yes you should be locked up. But then you miss out on a huge part of your life and you are separated from you mum and dad that must be awful. If you did shop lifting then you should get a telling off by the police but not locked up for that unless you do it lots of times.
Kayleigh, 13, London
I think that it's fair how the law is set. People should think twice before taking actions and if not then go through the consequences. Young people should learn the lesson.
Krissy, 14, Norwich
I think kids should be punished but locking them up is not always the answer it could make them worse in the long run.
Sarah, 15, Burton
I think that it would be scary to be behind bars. But I think I agree with Elycia.
Joe, 12, New York City
If we don't send young offenders to jail there is nothing to stop them doing it again and it encourages the belief that you will not be punished for your criminal actions.
James, 15, St Albans
I think that if you break the law, however old you are, you deserve to be sectioned from society. The younger the offender is, the more important it is to lock them away, to teach them morals. If you want to have a good time, don't do the crime.
Natasha, 13, Essex
Sending bad kids to jail is a good idea. I know some people in my class who have shoplifted before, and they went to jail for a day. It serves them right!
Hafsa, 13, Reading
Imprisoning children can be a good idea MOST of the time, but some children take it as an advantage to show off to others!!!
Attiya, 13, Leicester
I think it really depends on how serious the crime was. For instance if a kid murdered somebody then he/she should be put behind bars because they should be isolated from the world. If you are being locked up for something like shoplifting then you should be disciplined in a juvenile detention centre.
Elycia, 13, Stevenage
Some children deserve to be locked up, but for others I think there should be some kind of different, more suitable for kids punishment .
Mary, 11, Sheffield
I think people need to really look at the actual person who committed the crime. I don't think you can put offenders in boxes, and give them all the same punishment. You have to look at their background, their motive, who they were with etc... then see who was really guilty, and sort them out. Young offenders very rarely commit the crime 'just because they're bad'.
Jess, 15, Milton Keynes
When kids get locked up other kids will copy them and say it's 'cool' to be locked up, so its a bad idea.
Adam, 8, Bradford
I think putting kids in jail IS WRONG!! I think they must pay for it, out of THEIR pocket money.
Conagh, 9, Blackpool
I totally agree. Kids who break the law need to be punished. If it goes unpunished they could do it again.
Rebecca, 14, Essex
I think that kids that break the law should be locked up for a week and that should teach them to behave.
Kate, 10, Forres
Yeah, of course there's nothing wrong with it. If kids insist on getting into crime then that's their problem. It's not fair on the public to let kids off crimes just cos they're kids. They've broken the law - they deserve severe punishment. What if they decide that adult punishment is too strong? It's just not acceptable and very unfair to the public, especially those who could be at risk. I agree that it can't be very nice in that situation - but surely the kids in the situation thought about their actions before they committed the crime? That's my point.
Julia, 14, Sheffield
Prison is a harsh punishment, I don't think children deserve it.
Becky, 10, Oswestry
I saw the programme and I think the children need a bit more freedom. They should get counselling if they are really stressed. I think they should only be locked up for really serious crimes like murder not theft.
Marge, 15, Chepstow
Obviously they cannot stay out committing crime and breaking the law, so they deserve it.
Shreya, 9, Crawley
I think that it isn't right to put a child in jail because they should not miss their childhood.
Bethany, 10, Leeds
I actually think that imprisoning young criminals is the answer. They should understand what they did wrong. I don't feel sorry for the children locked up, they shouldn't have committed crime in the first place. And how can you 'break the law by accident'?
Natalie, 13, London
I know it seems a bit harsh but if you break the law you gotta pay for it!!!!!!!! I think maybe they should find another way to punish them coz it's not really right to be locked up at such a young age!
Ellie, 13, Devon
I totally agree - they deserve to miss out on childhood if they break the law. Don't do the crime if you can't do the time. There are plenty of people who deserve to be put away.
Jade, 15, Cannock
It might be the right thing to do to child criminals, but it makes me scared because I might break the law by accident and then the punishment would be awful.
Isabelle, 12, Manchester
I think that in some extreme cases, imprisoning children may be the only answer. But in most cases, I believe that children are simply messing around and get into trouble by accident - and accidents should be forgiven.
Charlotte, 15, Sevenoaks
Young offenders must be punished. If we're seen to go soft on crime, we'll simply encourage more of it.
Matthew, 13, St Albans
I think it would teach kids a lesson if they did REALLY bad things. If the crime wasn't major I don't think jail is the answer.
Fiona, 13, Blackburn
There are some seriously bad kids out there that are making people's lives unbearable. They need to be locked up and kept away from the rest of the world. However when released they cannot just be put back into the same insecure environment as they will just commit the same crimes again.
Robert, 15, Somerset
Kids do need locking up if they have done a bad crime like murder or assault. But I don't think they need locking up if they smash a car, or theft, because they are not learning a lesson about that.
Lucy, 15, West Sussex
I think it's a good idea to lock youths up! They committed the crime, let them pay for it. They have to learn that there are consequences for their actions and locking up children is a great idea.
Ali, 14, Devon
I think it is the answer. If you commit a crime you should be punished. If you're not punished you'll just do it again.
Ellen, 13, Bolton
Locking kids up isn't right! The ones it does work on just end up feeling worse than they should do! But it doesn't even work most of the time. It's the worst answer!
Stuart, 14, Blackburn
I feel sorry for the kids being locked up, but kids who do really bad things like steal or murder deserve it, but kids who have been behind bars for a long time feel upset because they should be outside rather than locked behind bars.
Georgia, 13, Lincolnshire
I don't think it would be very nice if I was ever in that situation. I wouldn't know what to do. I really think that there are other solutions than kids getting locked up.
Zoe, 11, Southampton
I totally agree with Chris, 14, Whitby. I also think it's harsh and if the kids do break the law they should get punished, but not locked up. If they do steel or burn a car etc they should get locked up for a day or something like that.
Bethany, 10, Leeds
I think it is a good idea because they will not do such a thing again but I also think it is bad because you would miss out on your childhood!
Jobhan, 13, Birmingham
It's tough. If you break the law, you should be punished, but I'm not sure locking kids up is the answer.
Chris, 14, Whitby