Pushing in your chair is important.  Hint: We both had Mrs. Krupich and this too, was her pet peeve.  My students push in their chairs. Or if I catch one not pushed in but lined up they have to come back and push it in, which puts them at the back of the line.  No 2nd grader likes to be last!  It's the best when I see one kid push in another's to 'save' them.