Things began to change, parents said. Surveillance cameras were installed to record both video and audio, for what David Centner said were security and insurance purposes. Leila Centner once remarked that children should be kept away from windows, for fear of radiation from 5G cell towers, another baseless conspiracy theory. (The windows at the preschool now have electromagnetic frequency “shielding blockers,” David Centner said in response to a question about the school’s 5G concerns.) The school opposed feeding children sugar and gluten and required that students have different shoes for indoors and outdoors. Some parents said they thought such ideas odd but inoffensive — unlike what began to happen with the school’s response to the coronavirus.