Two days after the Philadelphia School Reform Commission unilaterally canceled its teachers' contract and announced it would impose changes, hundreds of high school students went on "strike" Wednesday to support their teachers.

Dozens of students from Science Leadership Academy in Center City and as many as 175 from the High School for Creative and Performing Arts in South Philadelphia boycotted classes. They held peaceful, upbeat demonstrations outside the two magnet schools.

Twenty-five students from the Franklin Learning Center in Spring Garden demonstrated outside district headquarters at 440 N. Broad St.

"There's a lot of talk about teachers going on strike," said Cy Wolfe, a theater major at CAPA who helped organize what he called the "Philadelphia Student Strike."

"It's more important to us that they stay in the buildings until things get sorted out," Wolfe said.

Co-organizer Leo Levy, 16, a junior at Science Leadership, said the event was held "to show student solidarity with the plight of the teachers and to show how invested in a proper education the student body really is."

On Monday, the SRC voted to cast aside the expired Philadelphia Federation of Teachers contract and require teachers to begin contributing to the cost of their health insurance premiums on Dec. 15.

In anticipation of a legal challenge from the PFT, the SRC has asked Commonwealth Court to rule that the law allowing state takeover of the School District gives the SRC the power to scuttle the contract.

The PFT has not yet filed its response.

The takeover law also says Philadelphia teachers risk losing their credentials if they strike.

PFT president Jerry Jordan, who has harshly criticized the SRC's move, was to address his members and answer their questions during a phone-in session Wednesday evening.

Jordan, according to union members who listened in on the call, called every one of the PFT's 11,500 members to attend the next SRC meeting, set for 5:30 p.m. next Thursday at district headquarters.

Earlier, Fitch Ratings, which, among other things, rates public-issued bonds, lauded the SRC's actions.

Fitch said the SRC vote "provides a compelling case study that other financially distressed municipal entities might use to reduce labor costs."

But on the sun-splashed sidewalks outside their schools, students voiced their objections to the SRC's action. "SRC! Leave our teachers be!" was one of their many chants.

Outside Science Leadership, Juliana Concepcion, 16, a sophomore from South Philadelphia, held a handmade sign that read, "Students 4 Teachers."

"The teachers already do so much for us," she said. "It's just not right for the teachers to have their benefits cut like this."

Teens who hurriedly organized the class boycott via Facebook and Twitter said they chose Wednesday because it was scheduled as a half-day.

"We felt it would send a better message that we chose a day with fewer classes," said Levy, who lives in the Graduate Hospital neighborhood. "The public might assume this was an avenue for kids not to go to class. Hopefully, we've proved them wrong."

University of Pennsylvania history professor Thomas Sugrue made a detour on his way to work from Mount Airy to support daughter Anna, a junior at Science Leadership.

"Their voices are the ones who have been less heard in the debate about school reform," he said before tweeting a photo of his daughter.

The demonstrators were orderly but buoyant. At CAPA, band members provided music for the protest.

Outside Science Leadership, students even dropped their empty coffee cups into a plastic bin a school police officer had placed on the sidewalk to collect the demonstrators' litter.

They shook signs, chanted. and urged passing drivers to honk in support. The students whooped when a city sanitation truck responded with a sustained blast.

A handful of city police officers watched the students and cautioned them to stay out of the street.

Wolfe, the CAPA junior from West Philadelphia, said organizers were thrilled with the event. "I think it was fantastic," he said. "We had large turnouts at both schools, more than we expected." He said students would see what happens before deciding their next move.