Last year I found that we were wasting a lot of time at the end of the class lining up. It took too long, students used that transition time for talking, and weren't pushing in their chairs. To solve this problem, I created our line-up cards.
These cards hang on a push pin near the door. The "Star of the Day" is responsible for getting the cards and lining up his/her class by flipping the cards silently.
The first card signals for the students to stand up.
Second--push in their chair
Third-- go to their ABC order line.
At the beginning of the year, I go down each class list and alphabetically assign every student a letter to stand on for our line-up. The letter stays the same the entire year. I also have a picture of a little star at the beginning of the alphabet on the floor in case the class has a "line leader." Having the students line up the same way everyday prevents arguments about who is first or behind so-and-so and makes the line-up very efficient. If we don't line up quietly, then we lose a letter and practice first thing the next art class.
Watch Mrs. Harris' 4th grade class line up.