This document discusses adolescence as a period of "stress and strain" between childhood and adulthood. It defines adolescence as occurring between ages 10-19 years old, marking a transition initiated by puberty. During this time, adolescents experience significant physical changes through puberty as well as emotional and social changes. They develop new relationships with peers and struggle with identity formation. The document emphasizes schools and teachers can help foster healthy adolescent development by providing sex education, encouraging physical activity and social development, and understanding individual differences during this challenging transition period.