I've been teaching ESL since 1984, running since 1967. I have a B.A from the University of Alberta, a TESL Certificate from the University of Victoria, and an M.Ed. from Lesley University in Boston, MA.
While teaching essay writing for the last 15 years, I've discovered that if a student, ESL or native speaker, can master a few grammatical structures, he or she can paraphrase quickly and efficiently, thereby preventing plagiarism.