In the Medical Device Engineers Prototype Build and Lock unit, students become medical device engineers as they choose a real health challenge connected to an SDG goal, design a physical prototype device that addresses it, test it against their defined success criteria, redesign based on evidence, and lock the final version for the Q4 showcase. Set inside the Medical Device Engineers narrative, this 3-week flagship unit immerses Grade 4 students in human-centered design. What Students Will Do*