When I was teaching, the very first day of each class, I put this up on the overhead projector:
I don't make misteaks.
...and we discussed why such dumb errors were problematic for a writer.
Then I passed out a list of the the top 10 grammatical errors that writers make (a.k.a., the top 10 ways to drive your English teacher batty), and I taught my class how to avoid those mistakes. I warned them that if I ran into one of those errors in a student's paper after that, I would stop reading the paper and hand it back to him/her ungraded. It would then count as a late paper and the student would lose points accordingly until the paper was corrected and returned to me.
I told them that if I took my time to teach them grammar, then they should take the time to learn it.
You know, I never had to hand a paper back to a student. They made plenty of other dumb mistakes, but not the ones I told them to watch for. It kept me from going completely insane from the grammatical errors, at least.
Who says threats don't work? In combination with good, clear teaching, threats work wonders!
