Mayor Emanuel’s closing of 49 public schools in 2013 resulted in landfill-size heaps of debris. The artist John Preus, 44, was among the first to ferret through the piles, and within hours he had claimed four truckloads of items, all free for the taking. Preus has fashioned new objects from them, such as a swing cobbled together from student chairs and desks (pictured). “The history is there,” he says of the swing, part of the exhibition An Invisible Hand, opening May 21 at David Weinberg Photography ( “It’s a way to grieve and lament the loss on a public level.”