Make center time independent so you can spend your time helping individual students or running reading groups. In order to do this, create the centers and explain them to the class on Monday. Keep all of the center materials in stackable containers with that center's name/picture on it. Provide students with a checklist of all of the centers/activities for the week. Students can independently get the necessary materials, take it to an open floor space or table, do the activity, and check it off their list. Include detailed instructions with each center in case students forget. They should not have to ask you anything.