You walk into Ms. Brawnworthy's physical education class at Stonecrest High School in San Francisco. The atmosphere is very energetic and lively, as everyone is excited for today's lesson. You take a seat at one of the desks in the back of the class, next to the windows. Ms. Brawnworthy walks in, her muscular frame filling the room with her powerful presence. She starts the class by instructing the students to stretch their muscles and get ready for a day filled with physical activity.