LONDON -- Ukrainian children are going back to school today but for the majority of them, that doesn't mean going back to class.

More than 40% of Ukrainian students will have to rely on online or hybrid learning due to the lack of bomb shelters in schools and the danger of air strikes, according to Save the Children.

In Kharkiv, where a metro station is being converted into a classroom to avoid the back-and-forth travel to bunkers, most learning will be in front of a screen.

"Unfortunately, the security situation in the city does not allow schools to open. And we, parents, understand that the safety of children is the first priority," Valentyna Bandura, a Kharkiv resident and mother of a school-age child, told ABC News.

"A school in the subway is starting to work in our city," Bandura continued, adding that they remain uncertain exactly how they'll make it work. "This is the first experience not only for our city, but for Ukraine in general," she said.

Ukraine's Ministry of Education estimated that 1.7 million students will have limited in-person classes, of which one million will be fully online. That is because one out of four schools is not equipped with shelters that can accommodate all students and staff during air raid alerts, Ukrainian Education and Science Minister Oksen Lisovyi said last month.

Since the beginning of the war in February, 2022, 1,300 educational institutions in Ukraine have been damaged and 180 completely demolished. The schools that have survived Russian attacks in occupied territories, such as Zaporizhzhia and Kherson, constitute too much of a target for children to attend in-person classes there.

There are some advantages to online learning beyond safety, such as allowing refugee students to join from their host countries. But e-learning comes with many challenges, of which two are lack of equipment and internet connection.

"We hope there will be no power outages… And with just one tablet and two kids, someone will have to work on their phone at times," Bandura said.

Isolation, already a familiar situation due to COVID-19 and more familiar to families living in war zones, is another problem for children's well-being. "Keeping in touch with my classmates is quite difficult because we are used to spending time together in person," said Kateryna, Bandura's 14-year-old daughter. "But my class is friendly. In the summer, we saw each other several times."

"They spent time together and she really hoped that they would meet again in school, in their class," added Kateryna's mother.

For those whose school is resuming in-person learning, there are sobering additional concerns. Offline learning is possible only with reliable shelters against attacks, which the government is increasing.

"Our school has a renovated bomb shelter, a separate room for each class, so in case of an air raid sirens, not only they can wait till they finish but also conduct half-time lessons, which was the case last spring," Oksana Hryshyna, the mother of a 13-year-old in Kyiv, told ABC News. "I hope there will be no need to change the format."

Hryshyna and her son decided together that he would attend classes in person, although the school offered online learning as well. "In wartime, who will assess what is safer on the territory of Ukraine? The option of studying abroad, at a school in another country, my teenage son rejected," Hryshyna said.

Preparing her son's backpack, Hryshyna followed the rules of the school: an office tablet, a pen, a pencil, and a notebook. But she also included water and snacks, as well as a charger and a power bank, in case students must remain in the shelter.

"Education is important no matter how difficult the times are," Ukrainian President Volodymyr Zelensky wrote Friday on X, formerly known as Twitter, after attending the celebration for the 125th anniversary of Kyiv Polytechnic Institute. "Knowledge, education, and true competence – in good times, it is nearly impossible to win a competition without them, and in difficult times, there are no victories without them."

ABC's Natalya Kushnir contributed to this report.