The couple visited Task Force Liberty at the Joint Base McGuire-Dix-Lakehurst in New Jersey on Thursday.
The base is currently home to 10,000 Afghan refugees who are being supported by the Department of Defense.
During their visit, they stopped by a classroom full of children learning English.
The couple helped the students practice with many children eager to impress the royals with phrases like “Nice to meet you”.
Speaking about the day, a spokesperson for the couple said: “They asked staff about common terms in Dari, and left every interaction with children and adults alike saying ‘Tashakur,’ which means ‘Thank you’.”
The spokesperson added that the duke and duchess also led the class in a rendition of Head, Shoulders, Knees and Toes “which they shared was one of their son’s favourites as well”.
His parents have previously revealed that his first word was “crocodile” and that the Queen gave him a waffle-maker for Christmas last year.
Task Force Liberty was initiated in August in line with the withdrawal of American troops from Afghanistan.
More than 1,200 service members are currently stationed at the base to provide support to Afghans and their families.
Refugees are given temporary housing, medical screening and education while permanent homes are made available.
