Grady High School students protest the city's "turnaround" plan after a walkout today.

A new phase in school closure protests opened today as hundreds of students at William E. Grady Career and Technical Education High School walked out of classes this afternoon to protest the city’s plan to “turn around” the school.

The plan, which Mayor Bloomberg announced last month as a way to obviate negotiations about teacher evaluations with the teachers union, would require Grady to be closed and reopened with a new name and at least half of the teachers replaced. Grady is one of 33 struggling schools facing turnaround this year.

Grady students were the first to hold a closure protest since Thursday’s massive Panel for Educational Policy, where thousands of protesters railed against 23 school closure proposals that were approved. Now the city’s attention is shifting to the turnaround schools, whose closures are likely to come before the panel in April.

Department of Education officials explained the plan to confused students and parents at the Brighton Beach school late last month.

There was little confusion today as students executed a protest that was tightly scripted by members of the student government. After a rally on the sidewalk outside the school, students marched around Grady on a path that abutted the Shore Parkway and passed a police substation. Their cries of “Save our school!” caused neighborhood residents to lean out of windows and elicited a honk of support from an ambulance driver parked outside a home for the elderly.

Even one of the dozens of police officers who had been summoned to make sure the rally did not get out of hand showed compassion, telling a group of students, “I sympathize for you guys, I really do. I had two sons who graduated from here.”

Members of the student government said they hatched the plan to defend the school after learning about the turnaround plan last month. Grady went from a D to a B on the report card the city uses to assess schools, they pointed out, and some of its vocational programs — including construction and automotive repair — don’t exist in many schools. If the school changes overnight, they worried, the credits in each “shop” that students have accumulated might not transfer over.

“We really need our school to be saved,” said Marika Mattheson, the student government secretary.

Most students said they hadn’t found out about the turnaround plan or the protest until a student-led meeting on Friday or even this morning. A staff member who stood outside the school to corral students on the sidewalk — and who reassured some anxious protesters that they wouldn’t be suspended for leaving the school building — said students had kept the action under wraps until about half an hour before the 1 p.m. walkout time.

Students said they had planned an entire week of action that would include an hour’s trip to City Hall and even an attempt to “Occupy Grady” by camping in tents on the school grounds.

Jonathan Pamphile, a junior in the school’s media arts program, said students had already been working on a mural and other activities to celebrate Respect For All week, the city’s week to promote tolerance and oppose bullying. He said the week had an important message as the city contemplates Grady’s fate.

“We just want the mayor to respect us as students,” he said.

Oshin Powell, a senior, said she was determined to graduate this year and go to college. She said she would be let down if her teachers weren’t staying behind to be there when she came to deliver updates about her success.

“We have a real bond with the teachers,” said Kareem Lewis, 18. “We’re not going to have that bond anymore. … I just don’t know if Mayor Bloomberg will listen.”