In the frontline city of Zaporizhzhia, Ukraine, 74 fully underground schools now operate, offering children a rare chance for uninterrupted, in-person education. On the first day of classes Tuesday, students at the Sichovy Collegium descended into blue-painted concrete tunnels beneath a playground, safe from the near-constant threat of Russian drones and missiles. "It’s impossible to get an education now without going underground," said Oleksandr Lagin, a grocery store manager whose two sons attend.

While 3.6 million Ukrainian school-age children mostly study online or in basements during air alerts — Kyiv faced 158 minutes of alerts Friday, disrupting four of six lessons — Zaporizhzhia’s 10 underground schools, built with European funding, keep classes running. The city, less than 10 miles from the front, has endured years of bombardment.

Yulia Barabash brought her 13-year-old son Damir, who said, "I like studying here. The teachers are really kind, and it feels safe." He spends most days entirely underground, venturing out only during all-clears. A hallway memorial honors four former students and one teacher killed as soldiers.

Eight people died overnight in Kyiv, including six railway workers. Regional administrator Tymur Tkachenko urged schools to avoid crowds. For parents like Ms. Barabash, the bunkers bring relief: "I bring him here in the morning and don’t worry all day."