Here are a couple of links to useful internet resources you might use in class or mentor sessions.
http://education.indiana.edu/~tedfrick/plagiarism is an interactive quiz from Indiana. It uses APA as the citation format. It might be good for class to do together to spark discussion about plagiarism, paraphrase, quotes, and citation.
http://owl.english.purdue.edu/owl/resource/589/01/ features a "worksheet" that looks at plagiarism in general (no specific citation format). This would also work well as an in-class/mentor session activity or as homework that sparks a class discussion. It asks students to identify problems and offer solutions regarding citation in a list of passages.
Please share your favorite internet or print resources for teaching citation, quotation, paraphrasing, and avoiding plagiarism!