Supporters of public schools huddled up and bundled up in an overnight demonstration outside the Chicago Board of Education headquarters.
With temperatures in the single digits, the Chicago Teachers Union led the overnight vigil, at 125 S. Clark St., to protest charter school expansion ahead of a school board vote on 17 charter school proposals.
Protesters said the district left them little chance to be heard.
"We turned out to their public hearings and they chose to ignore us, as they always do, so we had to do something a little outrageous to get people's attention," said CTU Financial Secretary Kristine Mayle.
Critics maintain CPS should invest in neighborhood schools.
The financially-struggling district last year closed more than 50 schools and slashed $168 million from schools' budgets.