I am a stickler for organization. I like to prevent problems before they occur. Some preschoolers have meltdowns over the smallest things. This is just part of their development and personalities. I highly recommend some type of management system to determine the number of children that should be allowed in each center. Here is a look at the system I use.
First, you will need a low hanging corkboard or space on the wall about three feet wide. If you use wall space, use a decorative border to designate its border. I gave descriptions for seven centers so let us assume you use the seven centers. Make a picture sign as well as words to accompany the pictures.
Second, you should determine how many children could safely be in each center at one time. Let us assume you have 15 children in your class with seven centers. That is about two children per center with one extra child. However, we all know that some centers are going to be more popular than others are. Although, some centers will be big enough to accommodate more than two children at the time. Here is a sample of how I broke down the centers:
Art 3
Manipulatives 3
Writing 2
Library 2
Science 3
Blocks 4
Dramatic Play 4
After you decide the number of children per center, place something to attach nametags to under each center label. I used Velcro. You can use hooks or whatever works for you.
When introducing the activity board for the children, make each name marker unique in some way until children learn their names. After circle time each morning, children should decide their first activity for the day and place their name under the center of their choosing. You may or may not want to time the play in each center. I liked doing this because each child would experience each activity. I worked with a teacher at one time that made a sheet on a clipboard that listed each childs name on the left, the center names on the top and room for check marks to keep track of student activity.
Experiment with different management ideas until you find one that works for the children. Share your ideas in the forum for classroom management!

