America's strength has always been a function of its diversity, so it is troubling to see North Carolina's Wake County School Board taking steps to reverse a long-standing policy to promote racial diversity in its schools ["In N.C., a new battle on school integration," front page, Jan. 12]. The board's action has led to a complaint that has prompted an investigation by our Office for Civil Rights, but it should also prompt a conversation among educators, parents and students across America about our core values.

Those core values, embodied in our founding documents, subsequent amendments and court rulings, include equity and diversity in education and opportunity. In fact, on Monday we celebrate the life and leadership of Dr. Martin Luther King Jr., whose movement for racial equality inspired a nation and brought us closer to the more perfect union envisioned by our founders.

In an increasingly diverse society like ours, racial isolation is not a positive outcome for children of any color or background. School is where children learn to appreciate, respect and collaborate with people different from themselves. I respectfully urge school boards across America to fully consider the consequences before taking such action. This is no time to go backward.

Arne Duncan, Washington

The writer is U.S. education secretary.