For almost one third of Chicago Public Schools students, summer vacation ended Monday morning, when classes resumed at schools with year-round academic schedules.

CPS CEO Jean-Claude Brizard rang in the school year with a ceremony at Lindblom High School in West Englewood, one of 243 "Track E" schools in the district, WGN reports.

More than 650 volunteers called families over the weekend to remind them that classes resume this week, according to Fox Chicago.

For students, this year will feature more class time, with a new 7-hour school day in effect after a nasty tug of war between teachers and Mayor Rahm Emanuel earlier this year.

The longer school day may have been resolved, but the threat of a teacher strike still looms over CPS following a vote to strike over stalled contract negotiations in June.

"Parents are kind of just trying to figure out what's going on," Spencer Technology Academy Principal Shawn Jackson told ABC Chicago. "It's more so from the students. A lot of students are on the playground asking if they are going to start school."

Chicago public schools not on Track E begin classes Sept. 4, according to the CPS website.

Earlier on HuffPost: