Parents, teachers, and administrators in the Boston public schools called for changes to the teacher hiring and retention process Thursday, arguing that seniority protections too often allow poorly performing instructors to stay on the job.

The parents and educators spoke at a City Council hearing on the matter, attended by about 20 people. It was the second of two hearings convened by the panel’s Committee on Education focusing on the contract dispute between the Boston Teachers Union and the school department.

Seniority protections are among the points of contention in the dispute. Parents said Thursday that while their children have had many good instructors, some teachers do not belong in the classroom and have jobs only because of their experience level.

“I don’t know how you can get rid of those teachers, but [we] need them to go,” said Christine Poff, of Jamaica Plain, who has had children in the school system for 17 years.

Poff and others shared stories of apathetic teachers who failed to assign homework, engaged their class only in the presence of observers, and verbally abused students.

‘I don’t know how you can get rid of those teachers, but [we] need them to go.’

The parents said poor performance has not been the norm among their children’s instructors. But they said seniority protection has kept poorly performing teachers employed, sometimes at the expense of younger, more talented instructors in a process known as bumping.

Bumping occurs, they said, when senior teachers from closing schools are placed in other schools over younger teachers, regardless of their performance record.

Richard Stutman, the teachers union president, said by phone Thursday night that the union has reached an agreement with the School Department for a new teacher assignment process that gives more weight to principal and teacher choice rather than seniority.

“We do think the number of people bumped — their terminology, not mine — is exaggerated by the exceptions and not the rule,” he said. “By and large, the process we have in place works pretty well, and the new process we’ve negotiated will work even better.”

However, Melissa Granetz, assistant principal at the Donald McKay K-8 School in East Boston, said the current teacher assignment policy is harmful to schools and was a factor in her decision to take a job as a principal at an Oakland, Calif., charter school.

She said her resignation from McKay takes effect Friday.

“It really embarrasses me to be a part of a system that I think disrespects students and ultimately disrespects the truly outstanding teachers that I work with every day at the McKay School,” she said at the hearing.

The debate comes amid a recently brokered compromise between the Massachusetts Teachers Association, the state’s largest teachers union, and Stand for Children Massachusetts, an advocacy group. The two entities have hashed out a plan pending in the Legislature that would make teacher evaluations a key factor in staffing decisions.

Though the Boston Teachers Union and the American Federation of Teachers Massachusetts have voiced opposition to the plan, Councilor John R. Connolly, who chairs the City Council’s education committee, strongly supports the measure and recently offered an official resolution in favor of it.

He said Thursday that the assignment policy must change.

“I know that this is not right for Boston’s children,” he said.