The following universities have created tutorials with tests to help you prevent plagiarism in your assignments:
1. University of Missouri - The following tutorial includes quizzes to test yourself to see if you can recognize plagiarism, information on how to cite your sources and other helpful tips: MU Libraries - University of Missouri - Plagiarism Tutorial
2. Indiana University Bloomington - School of Education - This site includes cases, examples and practice tests for guests: IU Bloomington School of Education - How to Recognize Plagiarism
3. Colby, Bates and Bowdoin (CBB) Plagiarism Resource Site - This site includes a 15 minute self test on plagiarism with an overview of helpful terms: CBB Self-Test
4. University of Toronto - "How Not to Plagiarize" - this site includes a special section for English as a Second Language (ESL) students.
5. Cornell University - In addition to exercises, this site on "Recognizing and Avoiding Plagiarism" also provides links to citation management systems.