Within the span of two days, two New Zealand high schools were emptied of students and staff after volatile chemicals — long forgotten in storerooms and laboratories — reasserted their quiet danger. Defence Force disposal teams responded to both Mana College in Porirua and Horowhenua College in Levin, conducting controlled explosions to safely destroy the substances. No one was harmed, but the back-to-back incidents have drawn attention to a broader question about institutional memory and the slow accumulation of hazard in places built for learning. Education officials are now calling on schoo