Set the ground rules. It is important that your preschoolers know what is expected of them. Preschoolers are to obey the adults in charge and be kind to one another. Reinforce that all the children are friends and that everyone must be nice to one another. Instruct the children to share, take turns and to refrain from hitting or taking toys away from others.
Practice routines. Teach your students how to walk with the class in a line, without touching each other or anything else. Train the children to respond to a signal that means "silence". Raise your hand and say "Quiet Time". Some will do it, some not. Acknowledge individual students who obeyed quickly with a positive reply and description of what the student did right. For example, you could say, "Good job, Sally. You were quiet right away when I said 'Quiet Time'. Now, let's all try it again."
Correct negative behavior using positive instruction. "Don't" wears out quickly. In most instances, a positive correction works. For example: Mary is playing with the drinking fountain while Lauren is trying to get a drink. Instead of saying "don't do that", say "Mary, you are making it hard for your friend to get a drink. That is not nice. Please come back to the line and wait your turn." Now, gently put your hands on Mary's shoulders to turn her around to return to her place in line.
Redirect attention. When the negative behavior is not dangerous, behavior can often be turned around by changing the child's focus. For example: Timmy wanted to play with a toy that Sam was not ready to give up. Timmy got angry and yelled at Sam. Kindly explain that it's Sam's turn with the toy but Mark needs help putting together a puzzle. Then, walk Timmy over to Mark's table.
Place an ill-behaved child in "time-out". Sometimes it will be necessary to separate ill-behaved children from the group. Have a time-out location in your room that is different from the "quiet place". Place the ill-behaved child within view in the time-out locatiob for 1-5 minutes. Anything longer than five minutes and the time-out will lose its effectiveness, as the child is likely to forget why she is in time-out.
When the time is up, speak with the child asking if they are ready to be good and join the group. Have them apologize for the bad behavior. "Sorry" isn't enough. They need to say what they are sorry for. You will have to coach them. "Sorry, Tammy, for taking your crayon." Help them to know what to say and then help the other child to say that they forgive.