The link below is an interesting — and, in my opinion, correct — assessment of the challenges posed by the increasing number of F-1 visa students coming at the high school level, as compared to the J-1 visa students I work with. The mostly unregulated nature of F-1 visas creates problems for students as well as for host families, both of whom do not get the supervision or counseling needed for a successful exchange.
–The Exchange Mom
Weiss, Can International Students Save U.S. Schools?, The New Yorker, April 3, 2014.