It's still wrong!

I'm the Student Employee Manager in my office.  Most days I really like the title and the general responsibilities - they're mostly a good group and make my job pretty easy.  Plus, once I went to part-time from full-time I was relieved of the whole payroll duty which made me so happy.  Now, I really do just manage people and only have minimal paperwork bullcrap to deal with.  (To those of you who do payroll, boy am I glad I don't have your job!)
A few weeks ago, one of our student employees, I'll call her Sugarplum, asked if we could use her over the winter break and let us know she was available to work.  We thought about this a lot and ended up moving some numbers around in the budget and decided to hire her for the break (typically, we do not have student help over breaks).  I came up with a list of things for her to work on and everyone seemed happy.  Well, today I'm decidedly NOT happy with Sugarplum.  Now, I know I talk fast and I know that I sometimes assume people know what I'm talking about, BUT I've been working with Sugarplum for a few months now and I know that with her I have to a) slow down and b) explain things in detail.  Today, I put her on a project that I had actually given her over a week's notice to prepare for and I explained to her what needed done, both verbally and in writing, and she did it wrong.  Not once.  Not twice.  THREE TIMES, people!  Add to that the fact on her last try, I gave her a definite window of time in which to complete it and she was totally disregarding (is this grammatically correct?) the deadline so I felt compelled to stand right next to Sugarplum's desk and pretend to talk with a co-worker so she would actually work on it!  I mean, is that right?  I had to stand 4 feet away for you to do the task I assigned, you couldn't just work on it without me standing there?  REE-DICK-U-LESS!  Then she turns in after that THIRD TIME and it's STILL WRONG!  WTF??? 
The debate then centers around whether or not I spend time out of my day to re-do it and fix her mistakes or do I wait until Sugarplum comes in on Monday to point out where she went wrong and ask her to do it over again.  A.Fourth.Time.  Of course, because I work in an academic environment, the answer is I will gently and politely approach her on Monday and use this situation as a "teaching moment" to let her know that when a boss assigns you work, they do not accept nor tolerate it incorrect or incomplete.  BUT in my head, I'll be screaming at her to not be so f'n lazy!!  ARGHH!