This answer deals exclusively with non-immigrant students; that is, students who are not residents of the United States and who are in this country temporarily. If a student who is not a citizen of the United States nevertheless lives in Iowa with his or her parents, the school district of residence is required to provide a tuition-free education to that student. This is true even if the parents of the student are in this country illegally. See Supreme Court's 1982 decision in Plyler v. Doe, 457 U.S. 202, 102 S.Ct. 2382, 72 L.Ed.2d 786 (1982).
Under the Immigration and Nationality Act [8 U.S.C. section 1101], students qualify for either an F1 visa or a J1 visa.
The J1 visa is the more common classification for foreign exchange students. This visa is for a resident of a foreign county who intends to return to his or her country and who is a bona fide student who is coming temporarily to the U.S. as a participant in a program designated by the Director of the United States Information Agency for the purpose of studying. J1 visas expire after one year.
An F1 visa is given to a resident of a foreign country who intends to return to his or her country and who is a bona fide student who seeks to enter the U.S. temporarily and solely for the purpose of studying in an elementary, secondary, or postsecondary institution pre-approved by the United States Department of Homeland Security (DHS) - but is not sponsored by an exchange program.