When groups representing educators discuss the achievement gap, they often say, "We know what works.''

Far too often, though, that knowledge fails to produce results. Minnesota schools in general — and Minneapolis schools more specifically — continue to have unacceptably large learning disparities between some groups of students.

To change that, Minneapolis Superintendent Bernadeia Johnson wants more of them to operate like successful charter schools. And, as negotiations with the teachers union begin, she's rightly pushing for needed contract changes.

In a strongly worded speech last week before about 250 education stakeholders, Johnson said her administration's priorities for contract talks include stripping away outdated seniority restrictions; improving the ability to hire, retain and assign the best teachers, and expanding the learning day. She wants to promote teacher development and leadership while cutting compensation costs that do not support student learning. And she said about a half-dozen schools will be released from district and contractual rules to operate more independently — just like successful charter schools.

That approach deserves support. It's high time that school leaders and teachers put serious muscle into doing "what works'' for students. That should be foremost in the minds of educators on both sides of the negotiating table as they craft the next set of two-year contracts.

For example, Johnson questions the effectiveness of the longstanding steps-and-lanes teacher salary schedule that automatically awards increases based on longevity and additional educational credits or degrees. While experience matters and should be recognized in a compensation system up to a point, the steps-and-lanes system does not necessarily translate into improved instruction. But it does cost school districts more — even when no raises are negotiated.

Neither should staff assignments be based entirely on seniority. School leaders should have more flexibility to build teaching teams based on the needs of individual schools. The current Minneapolis teachers contract took some small steps toward providing more assignment flexibility, but it does not go far enough.

Johnson also wants to create a partnership zone of about a half-dozen schools that will be run by site-based teams. Teachers will have more say in how the programs operate, but they will need to agree to be governed by site-based rules.

The idea is to turn around some of the dismal student outcomes that plague the district — especially for lower-income students of color. Seventy percent of white students graduate on time, compared with 38 percent of African-Americans and only a quarter of Native American students. Low-income black students are six times as likely as white students to be suspended. They're also absent for almost a week more per year and are three times more likely to drop out.

Still, some schools here and nationally have done well with similar populations of kids. In Boston and several other cities, schools using Center for Collaborative Education methods have turned failing high schools into top-performing schools with 95 percent graduation and college placement rates. In Minneapolis, charter programs such as Harvest Prep/Seed Academy and Hiawatha Leadership Academy have closed the gap with their students.

That's why Johnson has wisely formed a partnership with Harvest to operate one district school and has plans to expand the model to more schools in the future.

Acknowledging some of the excellent work that Minneapolis teachers do, Johnson urged that classroom educators not be cast as "villains.'' And one of her goals is to better support teachers to take on leadership roles and shape how more independent schools operate.

This isn't the first time a Minneapolis schools chief has vowed to make dramatic changes. It will be a challenge for Johnson and the school board to stand firm for contract changes and take the inevitable pushback on unpopular decisions. To that end, she needs the community's support.

As Johnson appropriately summed up last week: "It's time to get off the dime, stop protecting the status quo, stop being satisfied with poor performance, to stop blaming others and get focused with partnership and innovation."