National Geographic Primary Readers is a high-interest series of beginning reading books that have been developed in consultation with education experts.The books pair magnificent National Geographic photographs with lively text by skilled children’s book authors across four reading levels. Every year like clockwork, animals both big and small are driven by a natural instinct to move in order to survive.On both land and sea, they fight the odds and the forces of nature to breed, feed, or lead and carry on for future generations.This level 4 reader is an introduction to the treacherous trek of the zebra, walrus, and Christmas Island red crab to overcome obstacles that include hungry cheetahs, stinging yellow crazy ants, and even their fellow species to make the often impossible journey of their lives. Level 4: Independent readerPerfect for kids who are reading on their own with ease and are ready for more challenging vocabulary with varied sentence structures.They are ideal for readers of White and Lime books.