Even with a war raging above them, seven-year-old Veronika Voronkina and her mother Natalia keep up with maths lessons.
These days, they calculate sums underground at a portable table in a dark subway carriage parked in a metro station in Ukraine's second-biggest city, Kharkiv.
Natalia and Veronika share the station's stuffy, stale air with hundreds of families and the elderly, most of whom spend their days horizontal on mattresses in a grinding monotony on the platform.
Life was not so mundane the day the war began.
"We woke up from the sounds of explosions, quickly got ready, took our documents, our cat, and ran to the metro station," Natalia Voronkina told the ABC.
"As we ran here, they were shelling right above our heads. It was very frightening."
Russian forces have pummelled Kharkiv in north-east Ukraine since invading the country eight weeks ago.
Now the fate of the city and the ambitions of Russian President Vladimir Putin are in the hands of troops positioned just outside Kharkiv.
They began a huge new ground assault on Ukraine's eastern Donbas region this week.
A 480-kilometre front line that stretches south of Kharkiv through eastern Ukraine could change the course of this war.
Heroiv Pratsi Station, near the heavily hit northern Kharkiv suburb of Saltivka, is packed around the clock, but there is no rush hour. The trains don't move anymore.
The only sign of daytime is when the fluorescent lights turn on.
The lucky few live in tiny tents for privacy or inside the subway cars, where blankets hang as walls from railings, which double as drying racks for clothes.
Most live on mattresses on the small patches of platform space they have staked as theirs, beside their most treasured belongings and pets.
One of them, 15-year-old Lev Chumak, hasn't showered since the war began.
"It's not cool here," he said.
"It's hard to clean your body. I can wash my head in the sink at the station, but not my body."
Each day, his father braves shelling and air strikes to bring the boy and his mother food.
Many on the platform are transfixed by their phones, their only contact with the outside world, other than a few minutes above ground each day for fresh air and some quiet, until it's punctured by the heart-stopping roars of shelling.
The lucky few live in tiny tents for privacy, or inside a train that sits parked at the platform.
Families have set up makeshift homes in the darkness of its carriages. Their walls are blankets hung from railings, which double as drying racks for clothes.
Ms Voronkina takes her daughter above ground occasionally to get some fresh air, but the possibility of shelling always looms.
"We stay close because all of a sudden there are explosions again and panic," she said.
"The child cries and we run back."
As Russia and Ukraine engage in a new grinding battle of attrition, this could be childhood in Kharkiv for a very long time.
Kharkiv is crucial to Putin's plans
Kharkiv, near Russia's border, is the jewel of Ukraine's east.
Until recently, it was a youthful and picturesque university city and cultural hub with gleaming gold-domed churches and a population of 1.4 million.
Now Vladimir Putin wants Kharkiv as a prize in his attempt to capture eastern Ukraine.
The new offensive is his latest brutal gamble after the embarrassing defeat by an outnumbered Ukrainian army three weeks ago of Russian forces fighting to seize the capital, Kyiv.
Kharkiv is under an intensifying assault.
Bodies of civilians lie in the streets of neighbourhoods where residents are trapped without power and running water, and with little food.
The horror of Russia's 'double-tap' attack
The ABC followed a local Red Cross team on an urgent mission to deliver food to scores of tenants stuck in a public housing block amid the relentless, earth-shuddering booms of shelling nearby.
En route through downtown Kharkiv, missiles struck a building just blocks ahead of the Red Cross team, sending out a cloud of black smoke.
The ABC joined them as they found a man and woman bleeding on the ground, surrounded by shattered glass.
The Red Cross team gave first aid while soldiers and paramedics arrived, but then several deafening roars signalled a second round of shelling.
The attack was a so-called double tap: A second hit just minutes after the first, putting first responders at significant risk of harm.
It was one of a series of indiscriminate attacks that caused scores of civilian casualties in days of intensifying shelling on downtown Kharkiv.
On that day alone, Sunday 17 April, at least five civilians were killed.
As soldiers, medics, the ABC and other media scrambled through a shattered shopfront window to take shelter, a lone Red Cross volunteer named Denis Potrenko braved the shelling to protect a wounded woman.
Mr Potrenko attempted to shield the woman, as he yelled to the wounded man out of reach to stay down, while soldiers ran past them to take shelter.
A journalist, The Sun's Jerome Starkey, stood frozen filming the courageous act.
Within hours, as the vision of Mr Potrenko's heroism went viral on Twitter, the young Red Cross medic pushed on with his duties.
Once it was safe to load the wounded into ambulances and evacuate, he drove with the Red Cross onward to its destination: A devastated neighbourhood near Heroiv Pratsi Station in which scores of tenants were holed up in public housing.
'We're under constant shelling and we're hungry'
Once he reached the neighbourhood, a cool Denis Potrenko calmed down desperate residents pleading for food.
"We're under constant shelling and we're hungry," one woman yelled as his team arrived.
"The shops are closed."
Minutes later, another round of shelling forced all to rush inside the building's entrance.
The booms were a common occurrence for these locals, already war-weary after just eight weeks.
"We hear this every day, throughout the day," Liudmyla Borysivna, 74, told the ABC after hiding in the doorway.
"Sometimes it's every 15 to 20 minutes, sometimes every hour.
"When we hear it far away, we don't run. When we hear it right here, flying above our heads, then we hide."
The residents are among hundreds of thousands of civilians who remain in Kharkiv in an increasingly catastrophic humanitarian situation, according to local Red Cross coordinator Oleksander Lebediev.
"The people left in Kharkiv were already the most vulnerable people," said Mr Lebediev, a 24-year-old political scientist who now witnesses daily horrors.
"Most are too old or sick to move somewhere else or too attached to their families, so they have to stay in a very dangerous area.
"All the houses around them have no electricity, water or gas."
With no way out, Alla and Viktoria shelter at home
Alla Oleksiivna cannot leave her apartment. She cannot seek shelter in the metro station.
Instead she remains in a small flat, with little protection from a Russian attack.
Ms Oleksiivna shares the apartment with her daughter Viktoria, 46, a former children's librarian who can no longer walk or talk due to a severe, degenerative form of epilepsy.
They are trapped by the persistent Russian attacks, which are worsening Viktoria's condition, according to her mother.
"Where should we run? She doesn't walk. I can't go abroad with her, so I only pray for peace," Alla Oleksiivna told the ABC.
Mr Lebediev said families like the Oleksiivnas were living in terrible conditions.
"Most of the people who are left are in poverty and are holed up in basements or hiding in their still-intact flats," he said.
He said it was "impossible" to establish evacuation routes for residents close to the frontline.
"It's hard for them to reach anyone because it's dangerous to move through the streets. They are constantly shelled," he said.
"Kharkiv's outskirts are hell."
For now, all Alla and Viktoria can do is wait in their flat and hope nothing hurtles towards them through the air.
"She's scared of course, and her seizures have become more frequent. She has five to seven a day," Ms Oleksiivna said of her daughter.
