A profile of dogs with jobs: guide dogs, service dogs, customs dogs, herders, and search-and-rescue dogs. More Than Man's Best Friend examines clever canines and the work they do for us. National Geographic supports K-12 educators with ELA Common Core Resources. Visit www.natgeoed.org/commoncore for more information.About the Author: Robyn O'Sullivan is the author of several National Geographic History and Science Chapters, including Jackie Robinson Plays Ball, The Wright Brothers Fly, and Your 206 Bones, 32 Teeth, and Other Body Math.