One lucky class of young Frozen fans got to meet Kate Middleton when she visited their classroom Monday in the Harlem neighborhood of New York City.

“They thought she was the princess from Frozen,” school administrator Rose Ann Harris said of the Duchess of Cambridge’s visit to Harlem’s Northside Center for Child Development. When a classroom of 3-4 year olds were asked if they knew who was coming to visit, one little girl shouted “Princess!”

The Duchess, in town with Prince William, visited the Northside Center—which specializes in educating children with developmental issues—with New York City First Lady Chirlane McCray. The pair joined administrators, volunteers and donors to wrap Christmas presents, including several toys from Frozen.

The Duchess and McCray were assigned to wrap a toy flower and a toy butterfly, but at the last minute, Harris suggested the Duchess wrap a toy Princess Elsa. “Does everybody agree she should be wrapping the princess?” she said. Sadly, Harris was overruled, and Kate wrapped a singing butterfly instead.

Northside Center for Child Development was founded in 1946 by civil rights leaders Dr. Kenneth B. Clark and Dr. Mamie Phipps Clark, who co-authored the famous “doll studies” that found that African American children preferred to play with Caucasian dolls. Their findings, which suggesting that black children had internalized many of the racist attitudes of the early 20th century, especially if they attended segregated schools, were instrumental to the Supreme Court’s Brown v. Board of Education decision, which de-segregated American schools.

While the Duchess visited Northside, her husband Prince William was meeting with President Barack Obama in Washington D.C. This is the couple’s first official visit to the United States. Kate is five months pregnant with the couple’s second child. Their son, Prince George, stayed home.

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Write to Charlotte Alter at charlotte.alter@time.com.