“I hope it’s enough,” said Serkan Erdogan, an English teacher at the Bakirkoy Cumhuriyet primary school close to the Marmara coast, where $315,000 was spent to add reinforced walls, jackets of fresh concrete and steel rebar around old columns and to make adjustments as simple as changing classroom doors to open outward, easing evacuations. “The improvements are great, but the building may still collapse,” he said. “We have to learn how to live with that risk. The children need to know what they should do.”In a fifth-grade classroom, the student training that goes with the structural repairs was evident as Nazan Sati, a social worker, asked the 11-year-olds what they would do if an earthquake struck right at that moment. At first a forest of hands shot toward the ceiling. Ms. Sati quickly told them to show, not tell. In a mad, giggling scramble, the students dove beneath their desks. But the threat for children, and their parents, also lies outside the school walls, in mile upon mile of neighborhoods filled with structures called gecekondu, meaning “landed overnight,” because they were constructed seemingly instantly as hundreds of thousands of migrants from rural regions flowed into the city seeking work in the past decade or two.