DEDHAM (CBS) – Defying an order from the state, Dedham teachers went on strike Friday morning in the first teachers’ strike in Massachusetts in 12 years.

Educators hit the picket lines at the high school and other schools in town around sunrise, forcing Dedham to close schools for the day.

The Dedham Educators Association approved the strike by a vote of 258-2 Thursday afternoon. They’ve been working without a contract for more than a year now. A major sticking point in negotiations is language preventing sexual harassment.

It’s against the law for teachers to strike in Massachusetts. Before the Dedham teachers walked out, the Massachusetts Department of Labor Relations issued an order not to strike.

“We know that it’s disruptive, and they know that it’s disruptive, but they know that it’s important and that our work environment is their learning environment,” said Dedham Education Association President Tim Dwyer.

The last teacher strike in Massachusetts was back in 2007 in Quincy. Teachers were on the picket line for five days. At one point, a judge ordered them back to work because they were breaking the law. When the Quincy teachers refused, the union was fined daily.

“It is illegal, it’s not criminal, and we spend a lot of time teaching our students to stand up for ourselves and stand up for what’s right, and our members decided that it was time for us to stand up for what we feel is right,” Dedham Educators Association member Rachel Dudley told WBZ-TV.

Another issue is cell phone usage by students. “Constantly in class it’s a battle,” Dwyer said. “To have kids not have their cell phones out, not have them on the desk, not be using them. And it’s a real problem.”

Superintendent Michael Welch said they’re ready to return to negotiations.

“Our very first priority is to get our students back in school we are so very proud of our school district and hard-working men and women who work together everyday to educate our children,” he told reporters.

The teachers got some national attention Friday morning when Vermont Senator and presidential candidate Bernie Sanders tweeted his support for them.

Right now there is a movement of workers across the country who are taking back their power at a scale we have not seen in recent memory. I stand with educators in Dedham, Massachusetts. This takes courage. https://t.co/KE1APXyI04 — Bernie Sanders (@BernieSanders) October 25, 2019

Sanders said their strike “takes courage.”

Massachusetts Congressman and U.S. Senate candidate Joe Kennedy also offered his support, visiting some of the teachers in Dedham at a rally.

“I am proud to stand with you today,” Kennedy said. “I want you to know that in me you you have an ally, you have a champion.”

Both sides say they are willing to negotiate over the weekend.