TORONTO -- An Ontario labour board ruling that declared a planned elementary teachers walkout an "unlawful strike" came too late to avoid a morning of confusion and uncertainty for students, parents and school boards Friday.

Parents had gone to bed Thursday night thinking public elementary schools would be closed the next day, only to wake up to the news that the teachers called off the protest after the 4 a.m. ruling from the Ontario Labour Relations Board.

Premier Dalton McGuinty put the best face on the dispute, saying the board's decision provides clarity about the illegality of teachers walking off the job to protest Bill 115, which the government used to impose contracts on school boards and educators.

"The threatened job action introduced a lot of uncertainty into the lives of young families today," McGuinty said.

"I want to thank parents for the roller-coaster ride they've been put on in recent days, not knowing exactly what would happen with respect to schools today."

As lawyers for the Liberal government and the Elementary Teachers' Federation slugged it out in a marathon session at the labour relations board -- which didn't even start until late afternoon on Thursday -- many boards decided the best option was to close schools Friday so parents could plan ahead.

But after the ruling, some boards, including Toronto, decided to open classes Friday, although many couldn't get their buses running.

Other boards -- including those in Ottawa, Windsor, Kenora and Thunder Bay -- decided there wasn't enough time to get schools operating, although some allowed parents to still drop kids off at school.

Some parents in Toronto were pleased to see the schools open Friday.

Patricia Policarpo, 36, said she was relieved she could take her six-year-old son to his Grade 1 class.

"I'm glad they put the school back on because figuring out what to do with my son for the whole day would have been a problem," she said.

"I didn't think there was enough notice given to begin with."

Kelly Zettel, 42, said the cancellation of walkout means a return to the usual routine for both her and her two children attending school.

"I'm relieved that I'm going to work and doing what I normally do on a Friday, and that my kids are going to be doing what they normally do on a Friday."

Some parents took to Twitter to express their frustration.

"So school is on? I'm keeping my kids home anyway," Sandy E of Toronto tweeted, adding, "Parents: please don't take it out on the teachers."

Paul Armstrong tweeted: "My kids won't be in school today. Our teachers told students it was a PA day..."

McGuinty said the labour board decision also prompted high school teachers to cancel the walkout they had planned for Wednesday. The Ontario Secondary School Teachers' Federation did not immediately return calls for comment Friday.

The ruling puts remaining questions about the legality of a bill that imposed contracts on some teachers "squarely in the sphere of the courts," McGuinty said.

"Putting students in the middle of a dispute undermines goals I believe we all share."

The outgoing premier, who leaves office later this month, called on teachers to resume supervising after class sports and clubs.

"There's an opportunity to begin laying groundwork for more productive negotiations next time," said McGuinty. "Resuming extracurricular activities would be an encouraging step forward."

The Progressive Conservatives said the Liberals should have taken actions months ago to impose contracts on teachers to avoid rotating strikes in December and the threatened walkouts Friday.

"It became abundantly clear in November and December that ETFO was not prepared to sit down with the government," said PC education critic Lisa MacLeod.

"It was equally clear that the government was not prepared to play hardball. We could have avoided the turmoil that faced moms and dads and students and teachers who want to teach, this week."

The New Democrats said the Liberals were to blame for the confusion and chaos in schools for imposing contracts on teachers.

"We saw this coming when 115 was tabled and this is where we are at, completely predictable chaos in our education system brought on by a Liberal government who didn't want to negotiate and simply wanted to impose contracts from the very beginning," said NDP critic Cheri DiNovo.

The head of ETFO Sam Hammond said he didn't agree with the ruling but would respect it, and told his 76,000 members to report to work Friday.

If they don't comply, teachers could face fines of up to $2,000 each. Trade unions that engage in illegal strike activity can face penalties of up to $25,000 under the province's labour laws.

ETFO and other supporters argued during the hearing that it wasn't a strike, but a political protest that's protected under the Charter of Rights and Freedoms.

Government lawyers countered that any withdrawal of services would be illegal, as the teachers were no longer in a legal strike position once the contracts were imposed.

Board chairman Bernard Fishbein said he wasn't persuaded by ETFO's arguments.

"Nor am I persuaded that the Charter protection afforded to speech -- whether 'labour speech' or speech generally -- outweighs the disruption that will be wrought on the statutory labour relations scheme acceding to ETFO's position," he said in reading his decision early Friday.

"Accordingly, the day of protest that ETFO has indisputably authorized and supported for Jan. 11, 2013 is an unlawful strike under the act."