The key to avoiding inadvertent plagiarism is learning how to correctly paraphrase. Harvard Graduate School of Education's well-developed tutorial on paraphrasing does not take long to complete and they offer a self-check worksheet. The tutorial references APA citation style, but the lessons on paraphrasing are relevant to all disciplines.
A free certification test provided by Indiana University at Bloomington's School of Education. Two version of the certification test are offered: one for undergraduates and one for graduate students. Instructors can easily validate certificates earned by students through this system.
Complete Guide to Referencing and Avoiding Plagiarism by 
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