The human body is an amazing ?machine? made up of different systems that allow us to do things like run, eat, and breathe. These systems work together to keep the body functioning normally and healthily. How does the human body actually work? What jobs do the systems perform? Welcome the sights and sounds of the world with the Footprint Reading Library. Accompanied by original video material developed by National Geographic Digital Media, this is the first non-fiction reading series to present fascinating real-world stories in three formats: print, audio, and video.
