The Navajo Nation operates Tséhootsooí Diné Bi'ólta', a Navajo language immersion school for grades K-8 in Fort Defiance, Arizona. Located on the Arizona-New Mexico border in the southeastern quarter of the Navajo Nation, the school strives to revitalize Navajo among children of the Window Rock Unified School District. Tséhootsooí Diné Bi'ólta' has thirteen Navajo language teachers who instruct only in the Navajo language, and no English, while five English language teachers instruct in the English language. Kindergarten and first grade are taught completely in the Navajo language, while English is incorporated into the program during third grade, when it is used for about 10% of instruction.