Human blood is simply amazing. From carrying oxygen to the body's organs to helping us battle against disease, blood has many jobs. However, one of them can be pretty gross--scabs! Whether gotten from a skinned knee or more serious injury, scabs are a constant part of life, especially in childhood. In this book, readers learn how and why scabs form--and why we should let them heal on their own. A diagram aids understanding of the essential body systems information and full-color photographs complement the approachable text.