The education and development of so many children was disrupted this year by humanitarian emergencies - we look at some of the stories of despair and dreams.
One in four of the world’s school-age children - nearly 500 million - live in countries affected by humanitarian crises such as conflicts, natural disasters and disease outbreaks.
About 75 million children are either already missing out on their education, receiving poor quality schooling or at risk of dropping out of school altogether.
Without safe places to learn, they are at risk of child labour, child marriage, exploitation and recruitment into armed groups.
Theirworld's #SafeSchools briefing - published earlier this month - said the number of attacks on schools is likely to be higher than the 400 verified for 2016.
One key proposal is that every country should sign the Safe Schools Declaration - an international commitment to protect education from attacks and stop the military use of schools. So far, 71 countries have signed.
The United Nations Security Council last month called for urgent action to protect children and education in conflicts. But of the council's five permanent members, only one - France - has signed the Safe Schools Declaration.
As everyone prepares to head into 2018, we look at the scale of the humanitarian crises caused by conflicts and natural disasters in some of the worst-hit countries during 2017.
Due to violence by Islamic State (ISIL), more than three million Iraqis have been displaced across the country since the start of 2014 and nearly 220,000 are refugees in other countries.
Mass executions, systematic rape and horrendous acts of violence were widespread, and human rights and rule of law were under constant attack. It was estimated that over 11 million Iraqis were in need of humanitarian assistance.
In a recent report called An Unbearable Reality, Save the Children revealed the extent to which the conflict has impacted on children’s mental health and psychosocial wellbeing.
The report detailed heartbreaking accounts from children displaced by the fighting. Children who had fled ISIL talked of “monsters”, “dead bodies in the streets”, “bloodied faces” and “bombs”.
They also spoke of their extreme sorrow of losing loved ones, experiences being felt by whole communities in a collective trauma.
In Mosul, where ISIL was defeated by Iraqi forces, UNICEF helped at least 35,300 newly-displaced children to go back to school in temporary learning centres.
At least 320 schools have reopened with help from the UN children's agency, allowing over 258,000 children to get back to learning.
“These neighbourhoods were gripped by violence,” said Peter Hawkins of UNICEF Iraq.
“Today, girls and boys are heading back to class. After the nightmare of the past two years, this is a pivotal moment for the children of Mosul to reclaim their education and their hope for a better future.”
More than 20,000 people have been killed and some 2.7 million people uprooted from their homes since 2009, as a result of Boko Haram's attempt to create an Islamic state.
The group, whose name loosely means 'Western education is sinful', has killed more than 600 teachers and forced over 1200 schools to close during its eight-year insurgency in Nigeria, Niger, Cameroon and Chad, according to the UN.
Three years ago, the abduction of more than 200 schoolgirls by the jihadist group in Chibok in northeastern Nigeria sparked global outrage and the #BringBackOurGirls campaign.
The militants have been driven out of most of the territory they held in early 2015. But this year they continued to carry out bombings and raids in northeast Nigeria, as well as in Cameroon and Niger.
In an effort to continue with their education, tens of thousands of children across the Lake Chad region were tuning into lessons broadcast over the radio.
The radio syllabus is providing lessons on literacy and numeracy, and staying safe amid the violence, to about 200,000 displaced and out-of-school children in the Far North region of Cameroon and Niger's southern Diffa region, according to UNICEF.
"The level of boredom among children in camps for the displaced is tremendous," said UNICEF spokesman Patrick Rose.
In October, we revealed that Plan International had a pilot scheme in Nigeria with mobile schools going into dangerous areas. Plan was working closely with communities under attack and - with the help of local people - teachers are brought in on motorised tricycles to give lessons for up to four hours a day.
After school finishes, the teachers leave the area quickly so they cannot be targeted by Boko Haram. The learning materials are kept in a secure location.
The latest crisis facing the Rohingya people started in August after 12 security officers were killed by ARSA (Arakan Rohingya Salvation Army) insurgents during attacks targeting at least 20 police outposts and an army base in Rakhine State.
In reply, the military responded with what they describe as "clearance operations," burning down villages and triggering a mass exodus of Rohingya to Bangladesh.
But stories of violence against women and children - villages burned, infants thrown in rivers, toddlers and mothers shot - abounded from makeshift camps in neighbouring Bangladesh, where survivors were struggling to find clean water, food and proper shelter.
Hundreds of children at the camps had been separated from their families and the numbers were growing daily.
In November, UNICEF said that since August 25 a total of 88,703 children under five had been screened for malnutrition. Out of 4405 children identified with severe acute malnutrition, 3596 had received treatment in the last week.
“Moreover, children, adolescents and women in both the Rohingya and host communities are exposed to high levels of violence, abuse and exploitation including sexual harassment, child labour and child marriage and are at high risk of being trafficked," said UNICEF.
"An estimated 450,000 total Rohingya children aged four to 18 years old are in need of education services."
A civil war, coupled with a severe lack of food, has wrecked education in South Sudan.
The world's youngest nation gained independence in 2011. But civil war erupted in late 2013 between soldiers of President Salva Kiir, an ethnic Dinka, and his former vice president Riek Machar, a Nuer.
UNICEF said in August there were 900,000 children in South Sudan who needed psychological help, with at least 150,000 of them living in camps. These are children who witnessed killings, abductions and sexual violence since South Sudan plunged into civil war in 2013.
School enrolment, which was 42% at the start of the war, has plummeted. Only 700,000 school-aged children out of a total of 2.5 million attend classes, UNICEF said.
One in three schools have been attacked by armed forces and 72% of children are out of school at primary level - the highest rate in the world. 76% of school-age girls are not in education.
We reported in June that nearly one million refugees were expected to have crossed the border from South Sudan to Uganda by the end of July, due to fighting. The situation was described as the fastest growing refugee crisis in the world.
Save the Children warned that children as young as 11 were making the journey alone, having fled their homes or villages due to the violence. And more than 900,000 refugee children could be shut out of education over the next three years.
With the war into its seventh year, more than 1.75 million children are out of school inside Syria and another 1.4 million Syrian refugees of school age are now living in Turkey, Lebanon and Jordan.
One-third of Syria's schools are out of use because they have been bombed, taken over by armed groups or turned into shelters for fleeing families.
In September, Save the Children said 55 of the 60 schools and learning spaces it supports for 20,000 children in Idlib and rural Aleppo had been shut for days at a time due to heavy shelling.
Theirworld has been campaigning since last year for international leaders to keep their promise to get every Syrian refugee into school. There has been good progress - but about 500,000 children are still not getting an education.
In April, the co-hosts of the 2016 Supporting Syria conference recommitted to their goal of "getting all refugee children and vulnerable host children in quality education".
This month it was announced that a $200 million World Bank project will help Jordan expand access to early childhood education and improve student assessment, teaching and learning conditions for Jordanian and Syrian refugee children. It will benefit about 700,000 children and help to train more than 30,000 teachers.
Two million children have had their education disrupted and hundreds of schools have been damaged or destroyed.
A child was dying every 10 minutes from "preventable causes", including malnutrition, cholera, diphtheria and - of course - the war itself.
Earlier this year, international donors pledged $2.1 billion in humanitarian aid for Yemen. So far only a third of the money has come in, said the UN. Last month, UNICEF said that more than 11 million children were in desperate need of aid.
"Today it is fair to say that Yemen is one of the worst places on earth to be a child," said Geert Cappelaere, UNICEF's regional director for the Middle East and North Africa.
"The war in Yemen is sadly a war on children," Cappelaere said, adding that close to 5000 children had been killed or seriously injured since the start of a Saudi-led campaign in support of the government in March 2015.
"Thousands of schools and health facilities have been damaged or completely destroyed," he said, calling for all parties in Yemen to take responsibility for the situation there.
Humanitarian emergencies can disrupt a child's education for months or even years. They mean children miss out on vital learning and are deprived of a safe place to be when they are in very traumatic situations.
In the summer, devastating floods affected more than 40 million people across South Asia.
Red Cross Under Secretary-General Jagan Chapagain said: "Almost one-third of Nepal has been flooded. One-third of Bangladesh is flooded. This is the worst flooding that parts of South Asia have seen in decades."
In India, more than 7000 schools were damaged or destroyed by the floods, said Save the Children.
In Bangladesh, authorities said 2166 primary schools were damaged by the floods. Classes were suspended at 855 secondary schools and another 393 educational institutions, including colleges, were being used as flood shelters.
In Nepal, the worst flooding in 15 years left many schools closed and others turned into shelters. The United Nations agency OCHA (Office for the Coordination of Humanitarian Affairs) said 383 Nepalese schools were being used as shelters.
"A large portion of schools are being used as evacuation centres, meaning children may be left on their own and without a safe place to go," said Shreeram KC of Plan International Nepal.
The earthquakes two years ago left almost one million children out of school in Nepal and destroyed or damaged more than 8500 schools and 14,000 early childhood centres.
A deadly storm in September hit the Caribbean. Irma, the most powerful Atlantic storm in a decade, caused widespread destruction across the Caribbean and the southern United States,, leaving 55 people dead.
It was a category five hurricane, with winds of up to 185 miles per hour, followed by two smaller hurricanes called Jose and Maria.
They wreaked havoc in a number of places where homes, schools and buildings were completely flattened and hundreds of thousands of people were evacuated to other islands and the US mainland. The hurricanes also severely disrupted children’s education.
In October Dan Walden, a specialist in emergencies for UNICEF UK, told Theirworld that £10.4 million was urgently required in donations to help around 357,000 children.
He said: “In Anguilla, there has been significant damage - also on Turks and Caicos Islands and British Virgin Islands. There are 17,000 people still living in shelters in British overseas territories.
“There are 39,000 children in east Caribbean needing our support. If we’re thinking about the whole Caribbean region, including Dominican Republic, Cuba and Haiti, that rockets up to 357,000 children.
“130 out of 132 schools were affected in Anguilla, Barbuda, Turks and Caicos and British Virgin Islands and that does not include Dominica."