At age 3, children are becoming more independent and more secure. When children learn about taking turns and cooperation from the adults around them, they increase their understanding of and appreciation for the feelings and actions of others. With guidance and good examples, children will gradually learn to cooperate when playing with friends. At this age, children are capable of working out their own solutions to disputes by taking turns or trading toys. Instead of grabbing, whining, or screaming for something as they did in the past, many preschoolers will ask politely at times. Caregivers can look forward to less aggressive behavior and calmer play sessions.
Shelov, S. P. (Editor-in-Chief). (2004). Caring for Your Baby and Young Child: Birth to Age 5. The American Association of Pediatrics. Revised edition. New York: Bantam Books.