WASHINGTON (AFP) – First Lady Michelle Obama on Thursday urged parents to teach their children tolerance in response to the deadly Tucson shooting spree that touched off debate about political rhetoric. Mrs. Obama, who joined her husband at a memorial service for the victims Wednesday, issued an open letter to parents. Children are struggling, she said, to make sense of Saturday's shooting that killed six and left 14 injured, including Congresswoman Gabrielle Giffords. "We can teach them the value of tolerance -- the practice of assuming the best, rather than the worst, about those around us," she wrote. "We can...