There are 350,000 sad kids in Chicago. The teachers union voted Tuesday to end a weeklong strike, securing what should be a double-digit salary increase over three years. Like a boxing match, the quarrel showcased two stubborn sides on the national stage. Union President Karen Lewis said that the teachers had struck down merit pay and a new evaluation system. Her opponent, Mayor Rahm Emanuel, did not give in to the request for a 30 percent base salary bump, and he lengthened the school day.