Over the past eight years Chicago teachers have done well, securing raises averaging 7% a year with no changes to their terms. The main sticking points now are teacher evaluations, compensation and the rehiring of teachers who have been laid off. These last two issues are the most significant hurdles (Mr Emanuel would like schools to be able to hire the best teachers, not the most recently-fired ones). But to keep the strike legal, the unions must insist that it is about nothing more than pay and benefits.