A visiting teacher was arrested in connection with a controversial display of the American flag at a Chicago art school. The exhibit has been a hotly debated subject for the past week, pitting artists and freedom of expression activists against veterans’ groups and others who say it is unpatriotic. Suzy Willhoft, 40, of Arlington, Va., was charged with desecration of the flag, a felony that carries a maximum sentence of three years in prison and a fine of $10,000. Willhoft was arrested after she stepped on the flag, which lies on the floor as part of an exhibit at the School of the Art Institute. The exhibit features the flag on the floor beneath photographs of flags, including some draped over coffins, and a shelf, which holds a ledger. Visitors may record comments in the ledger, but only the more agile can step to the ledger without treading on the flag. The legal counsel for the Art Institute maintains that the exhibit itself does not violate any flag law.