The document discusses the physical changes that occur during puberty for both boys and girls. It explains that puberty is triggered by hormonal changes which cause growth and development of secondary sex characteristics. For girls, this includes breast development, hip growth, and the start of the menstrual cycle. For boys, changes include broadening of the shoulders, deepening of the voice, growth of body and facial hair, and the start of sperm production. The document provides detailed information about the female and male reproductive systems and their functions during puberty and adolescence.