Classes were cancelled for about half a million students in Ontario on Monday as faculty at the province's colleges went on strike.

The labour dispute involving more than 12,000 professors, instructors, counsellors, and librarians began late Sunday, after the two sides couldn't resolve their differences by a deadline of 12:01 a.m. Monday. Both sides say there are no talks scheduled to end the dispute that involves Ontario's 24 colleges. Daytime classes at all colleges across the province were cancelled but many night classes continued.

The Ontario Public Services Employees Union says it is up to the College Employer Council, which bargains for the colleges, to restart talks. The union presented a proposal Saturday night that called for the number of full-time faculty to match the number of faculty members on contract but the colleges say it would add more than $250 million in costs each year. OPSEU bargaining team chair JP Hornick says the union remains ready to get back to negotiations.

"If the colleges approach the mediator, or us, and say they're finally willing to start talking then we would be at that table in a heartbeat," she said.

Hornick said the academic freedom and fairness for contract faculty remain the two biggest issues at the bargaining table. The union wants an even split between full time and contract faculty positions, adding that with a $1.2 billion funding surplus over the past decade it's not unaffordable for the province's colleges.

"The colleges are framing this as too costly," she said. "The proposals that we have put on are actually reasonable and in keeping with what's happening in post-secondary."

Don Sinclair, CEO of the College Employer Council, said the colleges have put a four-year-agreement that offers a 7.75 per cent pay increase on the table which it would like faculty to vote on.

"We have an offer that has no take aways and does ensure a reasonable increase to the faculty and partial load," he said. "So, I'm a little bit miffed, for lack of a better word."

Sinclair said he understands students will be frustrated by the strike, but urged them to be patient when crossing the picket lines.

"We will get through this," he said. "It could be a bit protracted, but I understand their concerns."

Advanced Education Minister Deb Matthews said she hopes the dispute is settled soon.

"I think we have to let the collective bargaining process work and give it the space to do that," she said. "But it's very important for students that they do get back to the table and find a resolution and get students back in the classroom."

More than 45,000 people have signed a petition calling for a tuition reimbursement for each day lost to a strike. Matthews would not comment on that idea or the possibility of eventual back-to-work legislation, saying she wouldn't discuss hypotheticals.

George Brown College student Hadi Syed said the picket lines took him by surprise when he arrived at the school on Monday morning. He was aware of the ongoing talks between the colleges and union but didn't realize they had soured.

"I'm really surprised it's come to this," he said.

Syed, who has come to Ontario from Dubai to take a one-year sports and event management program, said he's concerned that any change to his schedule could put a co-op placement set for next semester in jeopardy.

"It's going to be very challenging," he said. "It has to be squeezed into this semester. It can't carry forward to the next semester as maybe some other, longer programs would have. It is quite concerning."

Laura Hagarty, a third year landscape design student at Fanshawe College in London, Ont., said a two-month trip to Italy and Spain she and 18 fellow students were scheduled to take starting next week has been cancelled because of the strike. Beyond that disappointment, the labour action throws the whole semester into question, she said.

"With this strike it is almost certain we could lose out on our semester, which in turn results in a loss of graduating in April 2018," she said. "The (potential) loss of this semester means our graduation is pushed back, our careers are pushed back, and our lives are put on hold."