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. Determining the greatest invention of all time invites the greatest debate. From the internet to antibiotics, this reader explores our most significant contributions to education, technology, medicine, and transportation. Use the unique code inside the book to access the online reader, complete with videos and interactive exercises. Word count: 1622. Lexile Reading Level: 760L.