Last year state lawmakers in Illinois did their best to make a Chicago teacher strike impossible. They passed a new law that required at least 75 percent of the city’s teachers to okay any walkout in advance.

How did Chicago teachers respond? In advance balloting early this June, 92 percent of the city’s teachers voted, and 98 percent of those teachers voted to strike if contract negotiations broke down.

This near-total teacher support for the walkout that began last week shows just how intensely frustrated the city’s teachers have become. They’ve been teaching for years in schools woefully ill-equipped to serve the city’s students.