Calihan's school and a few others were closing for a couple days during the summit, which was to include the leaders of the 28 NATO countries as well as other world leaders. The meeting was taking place at McCormick Place convention center along the lakefront.
Security measures coupled with demonstrations promised to make getting around the downtown area and South Loop a nightmare. Churches in the area planned to stay open, but DePaul University's downtown campus was closing.
Old St. Mary's originally planned to be open May 18 and close May 21, but Calihan changed her plans after hearing that a local newscaster had announced the school would be closed both days.
"They made the decision for me," she told the Catholic New World, newspaper of the Chicago Archdiocese.
More seriously, she said, "we're on the path of everything happening between Grant Park and McCormick Place."
That means that, at best, it will be difficult for parents and teachers to get to the school because of the security measures in place and road closures in the surrounding area, she said. Even peaceful protests could completely cut off access, not only for parents and staff but for emergency vehicles.
"School administrators have to plan for the worst and hope for the best," she said.
The school closures didn't necessarily mean students would have days to make up, as some extra days were built into the school year.
Old St. Mary's Church planned to remain open for Masses despite the added commotion. The general thought was that parishioners are used to enduring Bears fans during football season and the Chicago Marathon in October, which goes right past its door, so they would be up for the NATO crowds.
Regarding the protesters, members of the Catholic Worker movement were holding nonviolence training for protesters, and on May 14 kicked off "a week without capitalism."
On May 16 about 150 protesters marched to banks and government offices calling for a yearlong moratorium on evictions and foreclosures in the Chicago area.
As of May 17, 12 people had been arrested at NATO-related demonstrations, according to Chicago police.
Media reports quoted Police Superintendent Garry McCarthy as saying 10 arrestees had been taken into custody in "voluntary" fashion. The Chicago Tribune daily newspaper reported one protester, a Los Angeles man had been, charged with a felony "for physically attacking a police officer."