Since the late 19th century, railroad companies in the United States had been struggling to track the 1) __________ of each railcar. David Collins addressed this challenge by creating KarTrak, a system that used optical sensors to scan colored bar codes. Around the same time, George Laurer developed the Universal Product Code (UPC) to track 2) __________ in the grocery industry. Innovations like these eventually 3) __________ to create the bar codes we use today, which helped 4) __________ merchandising and lay the foundation for the modern 5) __________. Engineers like Collins and Laurer systematically transform problems into 6) __________ and their profession has a(n) 7) __________ impact on shaping our world. They take a(n) 8) __________ and systematic approach to problem-solving and integrate ideas from 9) __________ streams of knowledge to solve real-world problems.