How can you tell the difference between an artery and a vein? Our resource tells you how! Learn the major organs of four body systems and how they work to keep us alive and healthy. We begin with blood, blood vessels and the heart. Next, we follow the path food takes from the mouth to the large intestine, and find out how food is turned into fuel. Then it's on to how the liver, lungs and skin all help rid our body of toxins. We look inside the kidneys and intestines, and finish with how a tiny sperm and egg cell can grow into a baby. Reading passages, student activities, and overhead transparencies all included.