Roughly 381,000 kids were sent home this week from Chicago Public Schools with a partisan letter blasting President Trump and Republican Gov. Bruce Rauner. Chicago’s WGN reported Tuesday that officials with CPS angered parents by handing out letters that excoriate Republicans — and Republicans only — for budget problems. A letter distributed on Monday begins by saying that Mr. Trump and Gov. Rauner “attack those who need the most help” as a segue into the state’s financial woes. “CPS cannot run the school system that your children deserve with the funds we have,” the letter says. “Under the law, CPS...