In the wake of an announcement earlier this month outlining New Haven-based charter school group Achievement First’s collaboration with New Haven Public Schools on a proposed experimental charter school, old tensions between the city’s teachers’ union and its charter schools have risen to the surface.

The proposed school, which has the working name “Elm City Imagine,” brings together more than a year of input from cognitive scientists, focus groups of local parents and staff, and other nontraditional schools across the country. But one vocal opponent to the plan has emerged in the New Haven Federation of Teachers, whose leaders argue that Achievement First has not been an ally of traditional public schools. Last night, the federation’s president spoke out at Monday night’s school board meeting to outline his concerns.

“We are absolutely opposed to this charter school,” said NHFT president David Cicarella, who cited discontent with the way Achievement First talks about public schools. “But is the answer that we’re never ever going to partner with Achievement First? No. It might be good for our kids.”

NHPS Superintendent Garth Harries ’95 defended Achievement First and the new charter school, emphasizing the district’s commitment to a focus on positive change through this initiative rather than conflict or rhetoric.

The model for the proposed school focuses on increasing classroom variety, including breaking away from the traditional large-group instruction in favor of small group, self-directed and experiential learning.

In addition to enhancing the range of instructional modes, Elm City Imagine would seek to increase support for students both on and off-campus with plans for peer-to-peer support networks as well as a personal “Dream Team” for each student, made up of family and community members who meet regularly with the student for check-ups.

“We opened Amistad academy 16 years ago, and while we are very proud of the success of so many of our students and the good work of teachers, we think that more is possible and even required,” said Achievement First CEO Dacia Toll. “It felt like the right time to take a fresh look at our school design.”

Cicarella said that one of NHFT’s primary concerns is that traditional public schools and Achievement First’s other charter schools do not operate under the same set of rules. He specifically referenced the NHPS policy that enables parents to transfer their children mid-year from charter schools into the traditional public schools, which Cicarella believes allows charter schools to push out students with behavioral issues.

However, Toll said a mid-year transfer is a parent’s decision, not one made by school administrators.

“They may become upset with a grade or a discipline decision and may decide to withdraw their student, but it is never because we have asked a student to leave,” Toll said.

Furthermore, Toll stressed that the number of transfers each year in New Haven is usually very small. According to Toll, charter schools traditionally only lose about 2 percent of students mid-year, a number she does not believe is much higher than the district average.

Harries emphasized that many districts across the country face a similar problem with mid-year transfers.

He also underscored that the Elm City Imagine proposal is just one facet of NHPS’s commitment to its School Change Initiative, which began in 2009. The initiative aims to build a wider portfolio of schools and increase graduation rates across the city, among other goals.

“We think that this has the potential to be a good thing for us to invest in, but this is far from the only thing,” said Harries.

Pending approval and finalization, Elm City Imagine is slated to open this fall.