Check out this great article on how a teacher uses turnitin to facilitate improved student writing. The article does a great job taking the reader through how to use turnitin. Turnitin is of course a writing tool not a solve all plagiarism checker.
*While I have been named a Turnitin Global Innovator Honorable Mention for my work in class and this site, I have no obligations financial or otherwise to speak highly of turnitin. I just find it’s a great tool as a teacher!