The information we have today about child development comes from a wide variety of sources. It has been said that the body of knowledge about children's development doubles every three years. Today's knowledge comes from studies in psychology, sociology, linguistics, health, anthropology, history, and education. This may sound overwhelming, but it serves as a reminder of how important it is to be constantly watching children to learn about their development. The recent changes in NAEYC's standards for programs and professional preparation of early childhood educators have been prompted by changes in the knowledge base of the early childhood profession. Major reports from the National Research Council have synthesized research on the science of learning and integrated child development studies (2000), again expanding our understandings of early childhood. NAEYC believes that all early childhood professionals should have a broad knowledge of development across the birth-to-age 8 range regardless of what age child or what kind of program they intend as a career focus. Many research studies and significant theories about development will guide us as we observe children and make decisions about their learning. Why study development? The answer is decision making. Using what we know and observe about children's development guides our decisions about their environment, their activities, and how we interact with them.

Using Developmental Guides

To assist us in understanding what we see when we watch children, there are normal developmental guides—indicators of what a typical 4-year-old or toddler looks like. Descriptions of normative development—what we know about so-called typical 4-year-old or 18-month-old children—are sort of an average developmental level. Talking about normative development comes with a caution to remember that each child is different. We must observe children with constant attention to the individuality of humans. There really is no such thing as a typical toddler or a typical 4-year-old. With young children especially, we know that development is happening so fast that their understandings and their skills change from day to day. For example, Keeley's language is expanding rapidly and her coordination is smoothing out right in front of her teacher's eyes. Her development may slow down for a few months and then suddenly accelerate. Children's rates of growth and development vary tremendously, so any developmental guidelines must take individuality into account.