The Purdue University Online Writing Center (the Purdue OWL) is renowned throughout higher education for the excellence and helpfulness of their extensive website, which is an extension of their on-campus Writing Center. Their discussions about Avoiding Plagiarism can be particularly recommended because the language is clear and aimed at people of all levels of understanding. Many faculty and writing instructors have found the resources under Preventing Plagiarism very helpful as a place to start the creation of assignments and assessments..
Avoiding Plagiarism (for everyone)
Preventing Plagiarism (learning objectives, sample teaching strategies and activities)