"When I write (or draw, paint, compose, etc.) something, I am presenting it as my work - a representation of my ideas. When the expressed ideas of another adds value to my work, and I include the expression of those ideas, then it is my responsibility to credit the creator of that expression; and that is not simply a matter of punctuation."
Start with teaching students how to better cite and reference their works. That should help prevent a lot of accidental or apathetic plagiarism.
“So we have workshops at the beginning of the year and a clearly defined punishment system, but a few times a year we still catch students and they face zeroes, they face suspensions,” he said. “Our official policy is third strike and expulsion, but we haven’t had to go that far yet.”