As a 2nd career teacher, I did this when my kids went to school in K, 1st, and some 2nd. I did not realize how much parents get on teachers nerves until I became a teacher. (Actually I do understand parents better than some). I honestly didn't know how much is involved in getting a classroom ready in the morning.
from a parent in the classroom
What I would do if I were you, is start hitting that parent up for work. "Can you take this to the office on your way down?" Can you take this to Mr. Jones?
Can you make copies for me? You never know, you might wind up help. (That is what I did as a parent -- I jumped at the chance to help out.)
Basically here are the motives behind lingering parents:
"If I am at school a lot, the teachers will get to know me and my child and will:..."
better understand him or her,
take better care of them,
choose them for activities,
want them in their class since I help out.
Parents that want to be involved in school want to know....
who are the "popular" teachers and kids?
who are the "smart" kids?
who are the "troublemaker" kids that I don't want my Julie going home with, etc.?
who are the teachers that don't do anything fun?
does the teacher remembers me?
what is the school gossip -- who is moving to what grade level, transferring or retiring?
I wasn't motivated by all of these, but I did see much of this going on.
I hope this helps.