As students return to school, one patterned textile now synonymous with uniforms will make its seasonal reappearance on pleated skirts, jumpers and ties: plaid. The design has long been a mainstay in both classrooms and in pop culture, bringing to mind the hilarious Irish teens of “Derry Girls,” the bold ‘90s fashion of “Clueless” or the provocative outfits of the early 2000s pop duo t.A.T.u. Plai