Cambridge Discovery Education Interactive Readers are the next generation of graded readers — captivating topics, high-impact video, and interactive exercises designed to motivate and engage. Boomerangs! Catapults! Sword rockets! Bat bombs! Throughout history, people have had no trouble finding ways to harm one another. Discover some of the strangest and most dangerous weapons that people have ever made. Use the unique code inside the book to access the online reader, complete with videos and interactive exercises. Plus, download a free e-book version of the reader!