Many animals live or work in groups. Some travel in large groups to protect themselves from predators. Other animals join together to hunt. No matter their size, groups are an important part of survival for many animals. Strength in Numbers: Animal Groups examines the social structures of animal groups, exploring why they form and how they help different species. Core Library is the must-have line of nonfiction books for supporting the Common Core State Standards for grades 4-8. Core Library Features: A wide variety of high-interest topics, Well-researched, clearly written informational text, Primary sources with accompanying questions, Multiple prompts and activities for writing, reading, and critical thinking, Charts, graphs, diagrams, timelines, and maps.