UNESCO considers that "providing education in a child's mother tongue is indeed a critical issue".
[1] In post-secondary, university and special education settings, content may often be taught in a language that is not spoken in the students' homes.
In situations where the medium of instruction of academic disciplines is English when it is not the students' first language, the phenomenon is referred to as English-medium instruction (EMI).
Public schools also have mandatory English and Spanish but only once or twice a week.
English is used, but in some schools, Spanish, French (in Louisiana), Hawaiian (in Hawaii), and local Native American/American Indian languages are used as well.