Ms. Hansen and the Explorers are very interested in learning--they want to know everything they can about the human body. But they aren"t alone! The Zelmans, Xeni and Zeno, have come from their planet to learn about Earth"s beings too! They travel through the circulatory system into the bean-shaped kidneys, and out through the urinary system to learn how the kidneys filter waste and perform its other functions. Come along as the Explorers and their favorite guests tour the human kidneys.