What makes Earth so special? Find out why our little planet is the perfect place for life to flourish inLife As We Know It.Life As We Know Itgoes back four billion years to a time when the earth was barely inhabitable, exploring the amazing story of how everything came to be despite the nearly impossible, hostile conditions that existed.Discover the six building blocks for all living things, unzip the DNA ladder, learn about the six different kingdom classifications, and more. Find out how 8.7 million species of plants and animals came from one single cell, and see how codependent Earth's delicate ecosystem is, with every organism and every living thing essential to sustain life.Broken up into manageable chapters from the smallest cells to the huge "Are we really alone in the Universe?" question, this refreshed paperback edition ofLife As We Know Itexplains complex scientific ideas with highly visual pages that have clear text for middle-grade students. Spanning the beginning of the universe to modern day,Life As We Know Itcelebrates everything we know--and even what we don't know--about life.