In answer to the quesiton: Is correcting a student's conventions errors effective teaching? Primary teacher Mary had this to say:
Little did I know that I was turning them off writing. I was focusing on what was wrong and not celebrating what was right (like great voice!). I didn't know any better. It was no wonder I would hear the grumbles as I would ask them to take our their writing notebooks.
It actually was very difficult for me to NOT focus on conventions at first. I had to get used to asking a child if they could read me their piece so that I would not be tempted to correct their mistakes.
I think that having a student edit their own piece it is not as discouraging to a child. Now, I might ask if they could read their piece and show me where there might be a good place to add some punctuation rather than me marking all over their paper.
(For more on editing vs. correcting check out this online lecture.