CHICAGO (CBS) — Chicago Public Schools parents breathed a sigh of relief – and perhaps let out a few sleep-deprived yawns – after the district reached a tentative contract agreement with the Chicago Teachers Union at the 11th hour before a threatened strike Monday night.

After nearly two years of negotiations, the compromise was reached about eight minutes before the midnight deadline, following a 12-hour negotiating session between CTU and officials with the nation’s third largest school district.

Had they not reached a deal, about 28,000 CTU members were prepared to start walking the picket lines at 6 a.m. Tuesday. Instead, teachers and students headed back to class, perhaps a bit tired, but relieved to have averted the second extended Chicago teachers’ strike in four years.

Outside Walter Payton College Prep High School on Tuesday, parents were happy to be dropping off their kids Tuesday morning, even if they were a little bleary-eyed after waiting up past midnight to find out if there would be a strike.

“We stayed up late last night expecting there to not be school, but we got to watch the Cubs,” one father said.

The seemingly cordial atmosphere around contract talks was a departure from four years ago, when CPS and CTU only agreed to a contract after a seven-day teachers’ strike.

“This is how civil conversation is done, and it’s great, and in fact it contrasts with the way which national conversations have been going these days,” one father said.

Many parents said they wished the two sides had reached an agreement a day earlier, so they and their kids wouldn’t have to wait up so late to find out if there would be classes on Tuesday.

Not everyone stayed up late to find out whether there would be a strike. Brianna Spinoza, a 5th grader at Skinner West Elementary School, went to bed Monday night expecting to be able to sleep in.

“I was surprised, because there was like a 90 percent chance it was going to be a stike, but wow,” she said.

One CPS teacher would not predict how he would vote on the tentative contract until he reads the fine print, but he said he’s grateful to be in class.

“I’m pleased that they were able to work something out. It’s nice to go to work and not have to be on a picket line,” he said.

The deal must be ratified by the union’s House of Delegates, and then by the full CTU membership.