(CNN) A New York teacher singled out African-American students and cast them as slaves in a mock "auction" as part of a social studies lesson in March.

An investigation by the New York Attorney General's office found that the reenactment had a "profoundly negative effect on all of the students present -- especially the African-American students."

"Every young person -- regardless of race -- deserves the chance to attend school free of harassment, bias, and discrimination," Attorney General Letitia James said in a statement.

"Lessons designed to separate children on the basis of race have no place in New York classrooms, or in classrooms throughout this country."

The incident happened in two fifth-grade social studies classes at The Chapel School -- a private school in Westchester County -- about 15 miles north of midtown Manhattan.

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