The Boston School Committee recently approved a proposal to convert Patrick F. Gavin Middle School and a Boston high school into charter schools in an effort to “accelerate students’ achievements,” according to Matthew Wilder, the committee’s director of media relations.

Based on the proposal approved on Nov. 3, the new charter middle school will open next fall and will be operated by Unlocking Potential, a nonprofit organization that seeks to improve underperforming urban public schools. The high school to be converted has not been identified but will be renamed the Green Academy, according to Wilder.

Though the students at the existing middle school showed some improvements in mathematics, they were struggling in other areas such as English, Wilder said.

“We realize that we really have no time to wait. We expect to see a rapid turnaround of the school.” Wilder said.

Current students at the middle school will have the choice to remain at the charter school or attend other public schools in the district. Other students who wish to matriculate at the charter school must enter a lottery, as required by the Education Reform Act of 2010 passed in January, which allowed Boston school districts to create in-district charter schools without seeking teacher unions’ approval.

“The mayor of Boston and the School Committee in Boston have become very upset with the fact that they are unable to renegotiate collective bargaining agreement that allows the school systems to make important changes and improvements,” said Paul E. Peterson, professor of government and director of the Harvard Program on Education Policy and Governance.

According to Peterson, charter schools bring in new management and are freed from teacher unions’ collective bargaining contracts that force them to keep ineffective teachers.

At the new charter school, teachers will be asked to reapply for positions or teach elsewhere. Tenured teachers who have worked in Boston for more than three years will have a job guarantee at another school in the district, according to Wilder.

As long as the collective bargaining agreements with the unions do not change, Boston will see a steady increase in the number of charter schools, Peterson said.

“With the passage of this law, you are now able to create some additional charter schools...[and] the pressure is going to continue to move in that direction,” he said.