This quiz application from the Sierra Club is perfect for teaching about the value of clean water and how one maintains water quality. As a substance, water constitutes 50 to 65 percent of each of us and covers 70 percent of the planet's surface. As a subject. water rewards contemplation with fascination. This engaging Q&A application presents 48 concise examinations of worldwide water and our often troubled relationship with it. What is Earth's wettest place? Where is the saltiest seawater found, and why does salinity vary? Consult this application for lucid answers rendered in appealingly casual prose. A lively test-your-knowledge game for multiple players, Water contains enough erudition to satisfy the solitary reader as well. A portion of this mobile application's sales proceeds are donated to the Sierra Club for environmental protection causes.