Why use Turnitin?
Turnitin is a flexible tool that allows you use it in the way best suited to your student group.
Originality Checking: At the most basic level, you can simply use Turnitin to screen your students' submissions for possible text-plagiarism. It is particularly effective for identifying collusion within a class group (or between years in a class group). It can also help you to identify where there are general writing problems that could be addressed through feedback and discussion with the class as a whole.
Improving Writing: Students can also benefit from accessing their own originality reports. In this case, it is recommended that you start with a low stakes (or formative) activity, where students can walk through the process of uploading their work and accessing the report. There should be some activity to support students in how to read the originality report, so that they understand how Turnitin works. Remember that not all colour is "bad".
Multiple Submissions: For students who have a good understanding of how Turnitin can support their writing, you might consider letting them have multiple submissions, so that they can learn from the originality report and make changes to improve their writing.
Online Feedback: Whether the students have access to reports or not, you can still use GradeMark to give rich feedback on assignments. Consider creating a rubric for the assignment, which will help to communicate your expectations, support feed-forward (how students can improve in future work), and make grading much easier for you. Audio feedback (max 3 minutes per student) can be a great way to give personalised feedback that conveys tone - often lost in written feedback.
Writing as a Process: Consider using PeerMark (also offered through Turnitin on Blackboard) to facilitate (anonymous) peer review for your class group. (Note that Blackboard also has a PeerReview tool)
For more ideas, watch this recorded webinar on Best Practices for Teaching with Turnitin.