The boy has tears in his eyes. He stares blankly at the floor, having long since given up any resistance. But the classmates standing around him show no mercy. One by one, they step out of the semicircle and punch him in the face, while the rest of the group laughs mockingly. A bystander films the scene on a phone. Videos like this have been circulating increasingly in Ukrainian Telegram groups and on TikTok and other social media platforms for months. For Nadiya Leshik, an education official, they are the expression of an underestimated but growing problem in Ukrainian schools. "At the start of the war, we were all preoccupied with other things," she said. "But since then, we've seen a steady rise in the number of cases of violence." For her, the reasons are obvious: minors are particularly affected by the consequences of Russia's war in Ukraine .…