In Syria's war-ravaged city of Aleppo, Abu Hussein hurries along little Ali, who has stopped just a few steps from school to buy a bag of potato chips.
"You'll be late!" he chides.
Ali is one of thousands going back to school in the city thanks to educators like Abu Hussein, who heads a school in the Sheikh Najjar industrial zone on the northern city's outskirts.
"Reopening the schools is an important thing to do," Abu Hussein says. "It gives a sense of normality even if the war continues a few kilometres (miles) away."
"The children of this area have been abandoned to their fate and we decided to look into the possibility of opening schools in the industrial zone so they wouldn't lose any more schooling."
When the Syrian civil war arrived in Aleppo, in July 2012, most of its schools and universities were forced to close.
During the winter, clandestine and makeshift institutions were set up by rebel forces, allowing some students to continue learning.
But "most of these children have lost an entire year of school," says Abu Hussein, a grizzled man in his thirties whose school in a former factory struggles to cater to several hundred students.
"We don't have enough books, one for every three students, and those we do have are old editions from years ago."
In the nearby Masakan Hanano district, another school set up by rebels and a Syrian NGO is also struggling to find supplies for 200 students.
"We need notebooks, pencils and other school materials. But we believe that we must resume normal classes so that the youngsters are not spending 24 hours a day consumed by the war and the bombings," says headmaster Abu Mohammed.
Life is even more difficult for the school that has been opened in the Saif al-Dawla neighbourhood, just a hundred metres from one of the most active frontlines in Aleppo.
The walls of the courtyard are a testament to the violence, pockmarked with shrapnel.
"The shells continue to fall daily but we pray to God that none will fall on the school," says Ahmed Saleh, a 22-year-old former maths student at university who has become a teacher.
The facility was opened with the support of Liwa al-Tawhid, a powerful Islamist rebel brigade that is close to the Muslim Brotherhood.
"Many of the underground schools have closed down, so we decided to open up the old schools," says Saleh.
Deserted, they had become headquarters for rebel brigades, which meant they often became prime targets for regime forces.
The Saif al-Dawla school is better equipped than some others.
"All the materials we have were smuggled in from the regime-held areas; we spent months bringing in books so we could resume classes," Saleh says.
Teachers with friends living in the regime-held parts of Aleppo enlisted them to help in the smuggling effort.
"The books we have are two years old, but for now we have to settle for them," says Saleh.
The schools in Masakan Hanano and Saif al-Dawla, both under Liwa al-Tawhid's protection, have around 1,000 students in total.
They study English, maths, religion and Arabic, but some subjects are off the curriculum for now.
"Our students don't learn geography or history. We have thrown out those books because they are full of regime propaganda and we don't want them to learn lies, the way we had to," says Ali, another teacher at Saif al-Dawla.
The 21-year-old, like Saleh, was forced to stop his own studies last year, and has been teaching since then. He earns 5,000 Syrian pounds ($44/33 euros) a month.
"The most important thing is to start working on the next generation of Syrians," says Ali.
"The future of this country is in this school, the teachers, doctors, lawyers and politicians.
"We must not lose the generation that will be the one that restores this country after the war."
In Salaheddin district, children roam the ruined streets on their way to local schools where the teachers, like 40-year-old religion instructor Samir Halak, are all volunteers.
"The teachers come because we want to change things, not to make a living," says Halak, who said he was fired from a government school for refusing to teach the government line on history.
"Before, the important thing was money. Now it is about the students and their future."
UNICEF, meanwhile, has condemned a regime air attack on Sunday on a school at Raqa 160 kilometres (100 miles) east of Aleppo that it says killed 14 people, mostly students.
A monitoring group put the death toll at 16.
Maria Calvis, UNICEF's Middle East and North Africa regional director, said it underscores "the dangers children face as they try to continue their education during the current conflict."