CHICAGO (CNS) — With world leaders descending on Chicago for the May 20-21 NATO summit, some Catholic school teachers were incorporating lessons about the political-military alliance for their students.

And with thousands of people coming to the city to demonstrate and draw attention to focus on issues ranging from war to the environment to poverty, they included a lesson or two about the history of protests, too.

“Since the time of Christ, people have been protesting,” said Mary Lee Calihan, principal of Old St. Mary’s School. “What’s a useful form of protest? What have people done? What has been effective?”

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.

News reports May 21 said at least 45 protesters were arrested the day before when they pushed through a police line outside the convention center and that up to then, the protests had been largely peaceful.

Among the demonstrators were dozens of Catholic Worker members from across the country. Protesters marched in Chicago’s loop and at the north side home of Mayor Rahm Emanuel. At least three members of the Des Moines Catholic Worker in Iowa were among those arrested.

A week prior to the NATO meeting, Catholic Worker sponsored nonviolence training for protesters, and on May 14 kicked off “a week without capitalism.”