Here is a great resource from Indiana University. The website provides tutorials and practice tests that students can independently complete that teaches them about plagiarism issues and how to avoid it. At the end, there’s a test that they can complete that gives evidence of their training and new knowledge.
I really like this site because it allows students practice before providing proof of plagiarism training (in the form of a passed test). I had my students complete the test and placed the results in their file. That way, no student can claim ignorance about plagiarism. Completing this website along with the Harvard Plagiarism training at the beginning of the year gives a nice beginning and mid-year training program.