A medium of instruction (plural: usually mediums of instruction, but the archaic media of instruction is still used by some) is a language used in teaching. It may or may not be the official language of the country or territory. If the first language of students is different from the official language, it may be used as the medium of instruction for part or all of schooling. Bilingual or multilingual education may involve the use of more than one language of instruction. UNESCO considers that "providing education in a child's mother tongue is indeed a critical issue".
Every public school uses Brazilian Portuguese as the medium of instruction, but no law prohibits the use of other languages in private schools. Many schools use other European languages (mainly because of the country's European heritage) such as English, German, Italian or French. Public schools also have mandatory English and Spanish but only once or twice a week.
American 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.