Educators today are well aware of how easy it is for students to plagiarise. There are even web sites out there set up so that students can buy papers and assignments... What students don't seem to be aware of is how easy the internet has made it for educators to catch them. Find a suspicious phrase/sentence/paragraph? Type some of it into Google, press return and, ta-daa!, the original source pops up.
A graduate student found that out today. The hard way. During his dissertation defense.