Three underperforming Boston schools are slated to undergo a four-month review, a move that could potentially avert a state takeover.

Superintendent Brenda Cassellius said she will assemble an "intervention team" and work with the Boston Teachers Union to assess problems at Charlestown High School, Madison Park Technical Vocational High School and the McKinley K-12. The teams will then make recommendations for improvements.

"I am appointing this intervention team to review data on student opportunities and outcomes recognizing that we have work to do to deliver on the promise of excellent and equitable education for all students," she wrote in letters to staff at the schools on Wednesday. "When a school is in need of support I have the authority to intervene."

The decision made some school staff anxious that the review could lead to layoffs, while others said they were apprehensive but feared that a state takeover would be worse. Cassellius also told the Boston School Committee about the plan on Wednesday night, framing it as part of a broader reinvisioning of the city's high schools.

Under the terms of the district's contract with the Boston Teachers Union, the superintendent can create a seven-member intervention team. Each school's team will include three members appointed by the union, three members appointed by the superintendent and one member who is jointly appointed. Each will conduct a four-month assessment of programming, leadership, facilities, enrichment opportunities and student support services. They will also conduct focus groups with students, families and eduators; review school data; and observe classrooms.

The teams' work will culminate in a set of recommendations to the superintendent about each school that Cassellius could accept, reject or amend.

All three schools have struggled with low graduation rates and serve large populations of students of color from economically disadvantaged families.

The McKinley K-12, a small cluster of school buildings serving about 350 students, had a four-year graduation rate of 29 percent in 2016, the most recent data available from the state.

Charlestown High School was designated by the state in 2019 as among the lowest-performing 10 percent of schools in Massachusetts. Hispanic and Black students make up the majority of the student body, and 74 percent of the school's students come from economically disadvantaged households.

Also in 2019, state officials classified Madison Park High School as needing "broad comprehensive support," its highest classification of need. Only 14 percent of its 10th grade students met state expectations on the 2019 MCAS exams, compared to 45 percent statewide. None of its students exceeded state expectations, compared to the state average of 19 percent.

In spring 2020, the state Department of Elementary and Secondary Education issued a withering review of Boston Public Schools that raised questions about whether receivership was imminent. Among the many criticisms, the report said 34 of the city’s schools had student populations who scored in the lowest 10 percent on the state’s MCAS exams. Shortly after the report's release, the pandemic forced the temporary closure of schools statewide.

On Wednesday, Cassellius outlined some of her planned changes to the School Committee.

"Boston has not delivered on a promise of a high-quality and rigorous education for all students," she said, "most especially for Black and brown students, as well as for students with disabilities, and our multilingual learners."

Drew Echelson, deputy superintendent of academics, echoed that sentiment. He said the district will refocus on good and effective teaching, specifically for students from diverse backgrounds, multilingual students and students with disabilities.

"We think it can be a really powerful lever for thinking about improvement," he said about the intervention process. "The goal here is to ... work together to ensure that we're clear on what the root causes are ... when students don't get what they need, and figure out what we need to do to ensure that they do."