Millions of kids across the UK got a day off school on Wednesday, because loads of teachers are striking.
They're part of two million workers who are not turning up for work in protest.
It's because they're unhappy with changes the government wants to make to their pensions - the money you get to live on after you retire.
Over half of state schools in England are closed, and half Northern Ireland's schools. In Wales it's up to 80% and in Scotland almost all schools are closed.
But it isn't just schools that are affected - other places that have been hit include hospitals, courts, government offices and job centres.
Heathrow Airport has warned that passengers could face delays of up to 12 hours, because immigration staff (who check passports) are striking.
We wanted to know what you were doing if you were off school - and what you think about the strikes - and you sent in hundreds of comments.
Here's a selection below - thanks for all your comments.
"EDUCATION is the most important thing in life. Teachers are always telling us that, but then they go on strike and we lose a day's worth of education. They should not go on strike!"
Millie, 12, Yorkshire, England
"The government should put education first and give the teachers a good pension. It's not good that I miss a day off school because I'm preparing for my GCSE's!"
Millie, 13, Norfolk, England
"I have to come into work with my parents and miss netball training at school! I have a very opinionated teacher and he totally disagrees with the strike because it means we're missing out on our lessons from today and that puts us behind in our learning!"
Josie, 12, Worcestershire, England
"I think it's right to go on strike because teachers should get more money as they work long hours for our education!"
David, 11, Lancashire, England
"My school is shut and I think I have mixed opinions about it. I had an English exam scheduled for today but, due to the strike, I'm not doing it. I'm worried about my education."
Imogen, 13, London, England
"I think it's good that the teachers are on strike because they should be paid more. They work really hard and it's really unfair."
Alex, 10, Essex, England
"I think it's right that teachers should strike. However, I wish that school was still on as I really like to go to school and learn."
Ed, 10, London, England
"My school and my sister's are both shut today, so my younger sister has had to go to work with my dad because he drives a minibus. My mum is still working in her office today and my other sister and I are at home by ourselves. This strike has definitely made childcare difficult for many parents around the country, but I think what the teachers are striking for is worth it."
James, 13, Sussex, England
"I think it's right to go on strike! The changes the government are making will affect my dad's pension and wages... and that means it will affect our whole family."
Riley, 11, Belfast, N. Ireland
"I think it's so unfair. My favourite teacher is going on strike and she works so hard for us. I think the government should give teachers MORE MONEY for their pensions!"
Moin, 10, Buckinghamshire, England
"My school is shut to pupils, but if my mum doesn't go in to work (she's a teacher) then she doesn't get paid. I have to go in with her because my dad is away. So although the school is meant to be closed, I still have to go into school!"
Zoe, 11, Worcestershire, England
"I don't think it's fair that teachers are striking because in that one day we are missing out on loads of education. However, it's not fair that David Cameron has made the people of England work longer for less. Nothing is fair!"
Hannah, 10, Chester, England
"I think that it sets a bad example to all children. It's unfair that so many children suffer whilst they fight to get their own way."
Holly, 10, Plymouth, England
"My school is closing and so is my brother's. My maths teacher is striking, but my school is making us work at home on the school website."
Chloe, 13, Oxfordshire, England
"I think they should be striking because they work hard to get their money and don't get that much anyway!"
Marina, 12, London, England
"My dad is a teacher and he stays up marking work till eleven o'clock every night. Teachers work very hard. My dad needs a break."
Lily, 8, Essex, England
"My teacher being on strike means I won't get to learn much. My mum had to take a day off work which isn't fair and she won't get as much money as usual."
Matthew, 9, England
"I think my teacher should get more money. She works very long hours, because when she gets home from school she continues to mark work and plan things!"
Courtney, 10, Peterborough, England
"I think they should strike. They work hard at school all day and they work at their homes marking work, so they deserve to be payed more."
Nick, 10, West Sussex, England
"I think of it both ways. I disagree with the idea because teachers say we should never miss school, but then they're off on a strike. However, I do think that the government is being very unfair to them."
Aimee, 11, London, England
"I don't think it's fair what the government are doing and the teachers are entitled to strike and have their own opinion."
Aliz, 12, Kent, England
"Teachers should be happy that they have a job and that they earn money because a lot of other people earn a lot less than them. I think they should be grateful with what they have."
Hannah, 12, Buckinghamshire, England
"My school is striking. The government are just being mean. Teachers have a right to protest."
Aisling, 10, London, England
"I think that it's causing people inconvenience, and it's selfish. I think they should do what they are paid to do. My mum now has to spend the day looking after my brother and sister who are younger than me."
Molly, 8, Essex, England
"I think that teachers over the country should be able to have their say in things. The government should be treating teachers well and not have a problem with the pensions. I think it is fair to have a strike."
Luke, 10, London, England
"I think that the teachers at my school work really hard and I hope that the strike works!"
Shruti, 11, Reading, England
"The strike is all about pensions, but if you have a pension then you shouldn't be asking for more money."
Jude, 10, Scotland
"My step dad is an English teacher at a secondary school and he is on strike. I think he deserves the day off as the union he's in isn't paying him enough!"
Katherine, 13, Dorset, England
"Why should they have more pay and a bigger pension when some people don't even have a lot of pay, no pay or any pensions."
Sean, 11, Carmarthenshire, Wales
"If teachers are enthusiastic about us getting our education, how can we if we're not getting taught! It's good that they are standing up for their rights but what about us?"
Aleisha, 12, England
"I think the teachers should strike. They work very hard and they deserve to make their point about pensions. We would do the same to prove our points."
Livvy, 12, Worcestershire, England
"I think the strike is unfair as I'm in a crucial year (GCSE's) and the teachers are doing something that they want to do but at the same time, they're disturbing our education."
Maliika, 14, Buckinghamshire, England
"I think that the strikes are good in some ways because we get to have a day off school but it's also bad because if the government keep it the way it is, then it will affect the younger generation of people in years to come. I hope that the government change things so that our parents/carers will have enough money when they retire."
Keziah, 10, Somerset, England
"I think teachers striking is a good and bad thing. It's bad because we miss a day of learning and good because the teachers are fighting for what they deserve."
Rebekah, 9, Hertfordshire, England
"I think that teachers do not have the right to strike. The government need the money to support the country and fund hospitals, schools, swimming pools and other public places."
Joseph, 10, Stockport, England
"I think it's a disgrace that the public sector are striking. The UK government is not a money distributing machine, especially in this time of global economic turmoil. Teachers already have some of the best pay/pensions/holidays in the world for their profession and this is just a show of pure selfishness for the greater people of the UK."
Calum, 14, Oxford, England
"I think that it is right for people to voice their opinions. We are lucky to live in a country that allows people to speak about matters that we feel strongly about. If this means that people have to strike to get their voices heard then that is okay!"
Evie, 10, London, England
"I think that the teachers are being really selfish. One of the reasons why they become teachers in the first place is because they want to teach us and help us with our futures. Lots of us are missing out on a whole day of education because of teachers who want more money. They should be setting a good example for being selfless and caring."
Indigo, 11, Bristol, England
"I believe that the teachers are striking for a very good reason. I think I would strike too if I had to work longer hours and get less pension money out of it in the end."
Rebecca, 13, Buckinghamshire, England
"My school is on strike like many other schools. My mum is not on strike and needs to go to work so I'm going to my grandad's house. Still, he always does fun things with me."
Poppy, 8, Glasgow, Scotland
"Britain's economy has been getting worse for a couple of years and the government has to make cuts somewhere. On the contrary, public sector workers shouldn't work longer hours and get less put in their pension. I'm undecided."
Rebecca, 14, Bedford, England
"I think that teachers do get paid enough. Some people only get paid a third of what teachers get paid."
Aimee, 13, England
"My mum is a teacher and I have to go on the strike with her!"
Olive, 11, London, England
"I'm glad we have a day off, and I don't mind missing work because we would only be doing Christmas things anyway. The teachers are not being unreasonable, they will be getting up at the same time anyway and marching!
Alex, 10, York, England
"It may be bad to miss a day of school but overall I think that all the people on strike tomorrow are campaigning for the future of others, not just themselves."
Martin, 15, London, England
"I think striking is a bad idea because it won't just affect the teachers and children, parents will have to find child minders if they're at work. It will end up costing us more money."
Phoebe, 11, Sheffield, England
"I think that the government is being selfish and unfair in making teachers work harder. It's their fault that they are in debt and they should not lower pensions!"
Sasha, 10, Northampton, England
"I agree with the strikes. It is unfair to work for longer and get less money, even though the country needs to make cutbacks!"
Kate, 11, Barnsley, England
"The strikes are having a huge effect on our learning. I have to gain 4 GCSE's by the end of this year. The teachers must accept that they have to work for less to help us achieve these goals, before we as the next generation become reliant on the help of the elder generation or benefits. We are missing out on learning time which we will never get back. "
Tabitha, 13, London, England
"My school is closed but the teachers have set the whole school homework to do on our day off!"
George, 13, West Sussex, England
"Public pensions are far better than private sector pensions. Teachers should stop complaining as everyone is feeling the pinch."
Harry, 13, Derbyshire, England
"I think teachers shouldn't strike because they get good pensions and pay. Other people don't get nearly as much."
Amelia, 12, Liverpool, England
"My school is going to be shut tomorrow and I`m going to miss my favourite lesson. Teachers say they want children to have good educations, yet we have the day off school, its Outrageous."
Donna, 9, Peterborough, England
"I think that the teachers should go on strike because the government aren't paying them enough, even though they have to work later."
Libby, 9, Staffordshire, England
" I'm in Year 7 and my school is closed but I have to revise 217 pages of French, learn a 46 line poem and memorise 2 songs. I'd rather be in school!
Beauty, 11, Greater London, England
"I think that teachers should strike because it's not fair that they should work more and get paid less pension money. Also, I don't mind missing a day of school!"
Maryam, 12, Greater London, England
"It's not fair that people are losing money and working longer, but there is an up side, a day off!"
Gethin, 12, Cardiff, Wales
"Nobody complained that our education would be interrupted when we had a day off for the Royal wedding! The strike is a good thing."
Max, 10, London, England
"My school will be closed too. Luckily my Mum is a teacher and she is going on strike so that she can look after me. I know that lots of my friends' parents are struggling to find someone to look after them."
Miranda, 10, Surrey, England
"My school is closed tomorrow because most of the teachers are striking. I'll be decorating my house for Christmas with my Mum and sister and I might watch some TV."
Monica, 8, East Sussex, England
"I think that the teachers have got to have a strike day because the Government doesn't give them enough money. I think the teachers at my school work hard."
Abdoulie, 9, Manchester, England
"My school is shutting too. I think that the Government are out of order and that they shouldn't make everyone work harder and longer for their money!"
Ben, 12, Kent, England
"I love school and I am worried that tomorrow I might miss out on learning something. I am going to spend the day in the library using the internet."
Dean, 8, Southport, England
"It's unfair only our secondary school is striking - why not all schools?"
Josh, 9, London, England
"I think they should go on strike because most teachers deserve to get the money as they work hard… and it gives us a day off!"
Holly, 12, Southampton, England
"I think it's good because we get a day off. I didn't know that we don't get paid after we stop working."
Stuart, 10, Inverness, Scotland
"I think that it is completely inappropriate. Even though I understand that the public sector think the cuts are unfair, they should think of other people - my dad doesn't earn enough to even have a small pension."
Abigail, 11, England
"I think it's a bad idea that the government want to change teachers' pensions because it's hard work being a teacher and most of them are excellent (especially mine)! If the government change their pensions then they might not have enough money to live off after they finish work."
Grace, 9, London, England
"I don't think it's FAIR because my brother and I go to the same school but he gets a day off and I don't!"
Chloe, 10, Birmingham, England
"My school is closed tomorrow and it's my birthday!"
Imogen, 10, Somerset, England
"I am in Year 6 and I do not think it is right that we have the day off school because we need to learn."
Ellie, 10, Essex, England
"My school isn't shut although loads of the teachers are striking. Some different people are going to be teaching us, like heads and progress managers. The one good thing is my food tech teacher isn't striking, so we get to make carrot cakes!"
Grace, 11, London, England
"I'm going on the protest march with my parents."
Niamh, 10, Glasgow, Scotland
"I think that they shouldn't go on strike because they are causing an inconvenience for everyone else."
Charlotte, 9, Derbyshire, England
"Our school is not closing but many other schools are. The kids there think it's a good thing and do not realise that the government's decision could affect us in the future."
Emily, 10, Kent, England
"I think it's great that they are fighting for their future. David Cameron called the strike 'unjustified'. His budget cut plan is unjustified."
Kieran, 12, Cardiff, Wales
"My school is only open for 60 pupils and the parents have to sign their children up to go to school (only from years 7 and 8). I think the strike is good thing, but not because I get the day off. I don't think it's fair for people to work for longer and get paid less."
Taya, 14, Isle of Wight, England
"I'm so happy because I get a day off school tomorrow! But some schools like the one my mum teaches in are still kept open, even though there are not enough teachers to give the pupils proper lessons! I think striking is quite bad and selfish because while the teachers are trying to get what they want, they are interrupting our education!"
Zaynab, 12, Watford, England
"My school is not open tomorrow either. I'm going to take the advantage to get ready for Christmas. I'll help decorate the tree, wrap up the presents I've already bought and maybe I'll watch a film."
Amber, 10, Essex, England
"Our school is closing on Wednesday because most of the teachers are on strike! That means I get to miss maths, which is very good news."
Isabel, 9, Buckinghamshire, England
"The teachers are striking at my school so we get the day off. My teacher doesn't agree on the striking and I don't think this protest really matters. I don't know what to do on my day off."
Maryanne, 11, Yorkshire, England
"It's quite hard to understand all of the details about the strike. I think it's lazy that the teachers take a day off. They get paid to do their job, so they should just do it!"
Annalise, 11, Manchester, England
"On Wednesday, I have a day off because of the strikes and I'm doing my Grade 1 piano exam!"
Milly, 9, Hampshire, England
"Tomorrow for the strike me and my friend Heather are going to have a day of retail therapy and then a sleep over! Should be fun!"
Leah, 13, Worcestershire, England
"Yeah, we have a day off because they're striking again. I think the strike is a bit pointless."
Abbigale, 12, Sheffield, England
"I'm going to spend my day off out in the shops as I need to get a new pair of school shoes."
Josh, 13, Lincolnshire, England
"I am very pleased about the teachers' strike because it's my birthday on the day of the strike! I'm really happy!"
Olivia, 12, Swansea, Wales
"On Wednesday our school is off, but we're having a Christmas concert on Tuesday and Wednesday so we still have to go! It's going to be great!"
Holly, 12, Somerset, England
"My school is not going to close because only a few teachers are striking."
Freya, 10, London, England
"I'm going with my mum to her dancing class and then I'm choosing things for my new bedroom which will be Blue Nose Bear theme! Hooray!"
Ellie, 9, Hertfordshire, England
"I think that having a day off school rocks! It means I can watch back-to-back episodes of CBBC Roar!"
Emily, 12, Suffolk, England
"On my day off school I'm going to the shopping centre with my mum, nan and granddad because it's my granddad' s birthday! I'm really pleased to be having a day off school!"
Holly, 11, Hampshire, England
"I'm off tomorrow and my parents are making me tidy my room... please help me!"
Grace, 12, Isle of Wight, England
"My school is going be shut and so are my brother's and sister's. I don't understand how the teachers say that it's very bad to miss a day of school and yet they're striking!"
Rahila, 11, London, England