http://www.plagiarism.com/self.detect.htm

both of these are used by teachers in North Carolina where I live.

Rightly or wrongly, most students are so tech savvy that they gravitate towards online research (which I think is fine, considering that peer-reviewed studies have found Wikipeida to be on-par with paper sources). But if they have plagarized that online research, good old search engines will tell ya!

Meaning:

to steal the words, ideas, etc. of another and use them as ones own. Literary theft.

Why would you want a website to steel other people’s work…

http://www.yabloog.com/check_plagiarism_for_free.html

all my teachers use it.