An individual progresses from childhood to adulthood during the decade of adolescence-ages 10 to 20, approximately. This progression includes not only the physical development of puberty but also the psychological and social transition needed to establish an adult identity. Adolescence is characterized by change. A young person comes to terms with body changes, copes with the awakening of sexual feelings and development, plans for a societal role, and ultimately achieves independence. While the teenage years often are described as tumultuous, insecure and rebellious, these stereotypes do not characterize all situations, and we must keep in mind the power that our stereotypes have on teenage development.
The adolescent growth rate is second only to that of a newborn infant and most often occurs in middle school. The development of a positive self-concept is crucial at this stage. Body size and shape, the timing of their development compared to their peers, and feelings of anxiety about these changes are important issues. Students are worried about whether or not they are "normal” and if their classmates accept them. Typically, weight almost doubles and height increases by approximately 25 percent. For example, "at the age of 12, an average boy may weigh 70-80 pounds and stand about 56 inches tall. Within 7 years, he may weigh 150 pounds and measure almost 70 inches” (p. 529). Girls undergo a similar dramatic growth spurt that usually occurs 2 years earlier than in boys. However, growth patterns vary and not all children grow according to established patterns.
Sexual development is a large part of the physical adolescent. In girls, the first physical signs of sexual development are the budding of breasts, usually between the ages of 9 and 13. Not uncommonly, one breast may begin to develop before the other, or the breasts will be asymmetrical. This is very normal, and it is important that the girl knows this because it can appear to be a cause of concern.