My school requires us to scan all papers through Turnitin.com.
What?!!?? What do you mean "requires"? It's like your teacher told you "you must buy a X brand laptop to use on my course; otherwise I'll fail you". Turnitin sux and they use your copyrighted work to cash in. Then they store your papers forever to "compare" results of other works with your work. How much commission do they pay you??
Teachers are lazy and think they can "require" the student to do the job for them. What kind of world do we live in?
Forgot to add - I wonder who's "great" idea it was but it was "smart"... As far as I know teachers require the students to submit papers to Turnitin THEMSELVES. Then, when there's a problem, they think they will not be liable for the copyright infringement.. because the student - not them - submitted the paper to the turnitin system.
Smart...