The human body is amazing. Your blood makes up about 8 of your body weight. On average your heart will beat more than 3 billion times in your lifetime Doctors and scientists make choices every day about how to keep our bodies going. But what would you change if you could Would you choose to have super strength or super speed Would you rather have no bones or no muscles It’s your turn to pick this or that About the Author Kathryn Clay has written more than 40 nonfiction children’s books about everything from dancing to dinosaurs. She also teaches college writing courses. She has a Master’s of Arts in Literature from Minnesota State University, Mankato. Kathryn lives in southern Minnesota with her husband and daughter.