The effort to reopen schools shut by Hurricane Sandy presented officials with a tangled puzzle and New York City’s 1.1 million students with a drastically altered landscape... Cots lined the hallways, and toilets were limited or clogged, so some evacuees went to the bathroom on the floor. Volunteers, gagging at air made more fetid by unwashed bodies, took to wearing masks. “We gave them wipes,” a volunteer said, “but there’s only so much you can do with wipes.”