WASHINGTON — To ensure that all students – regardless of race, ethnicity or economic background – get equal access to the best teachers, Kentucky plans to enhance mentoring for new teachers. Massachusetts will seek to raise standards for teacher education programs, and Rhode Island and Nevada are looking at financial incentives to attract and retain teachers.

The four are among 16 states, including Maine, that won federal approval Thursday for plans to improve teacher equity, as required under the No Child Left Behind education law.

The plans focus on mentoring new and existing teachers, improving teacher preparation programs, eliminating teacher shortages and giving financial incentives to teachers who work in lower-performing schools.

All 50 states submitted plans; the Obama administration is still reviewing the other plans. States could lose federal dollars if they don’t have adequate plans to address gaps in the distribution of high-quality teachers across school districts.

On Thursday, the department endorsed teacher equity plans by Arkansas, Connecticut, Delaware, Indiana, Kentucky, Massachusetts, Maine, Missouri, Minnesota, New York, Nevada, Oklahoma, Rhode Island, Pennsylvania, South Carolina and Wisconsin.

“All parents understand that strong teaching is fundamental to strong opportunities for their children. We as a country should treat that opportunity as a right that every family has – regardless of race, ethnicity or national origin, ZIP code, wealth or first language,” Education Secretary Arne Duncan said in a written statement.

The department launched the effort last summer, setting aside $4.2 million to build a network of experts to help the states develop and implement the plans.

The Maine plan includes multiple strategies, including improving mentoring programs for teachers; requiring teachers and principals to do training and undergo student teaching experiences in high-poverty, isolated and high-risk schools; and providing “longevity bonuses” for teachers and principals who serve for at least five years in identified high-poverty, isolated or high-risk schools.

“We are delighted that the hard work of the staff at the Department of Education here in Maine has gained the recognition of our federal counterparts and helped create a better learning environment for Maine students,” said Maine’s acting education commissioner, Tom Desjardin.

In Nevada, part of the focus will be on keeping experienced teachers. The state has a new law that established a performance pay system for the recruitment and retention of teachers and administrators focusing on the lowest-performing schools.

According to federal Education Department statistics, black and American Indian students are four times as likely as their white peers to go to a school where more than 20 percent of teachers are in their first year. The same data show that’s three times as likely for Latino students.