This hands-on, activity-based lesson will introduce students to design thinking and to MIT D-Lab's User-Centered Design process - a framework that develops solutions to problems by involving the user perspective in all steps of the problem-solving process.  User-Centered Design is an iterative process through which we try to understand the user, challenge assumptions and redefine problems to identify alternative strategies and solutions. Through this lesson, students will learn an approach to problem solving. While the lesson may or may not inspire students to pursue engineering or product design careers, it will certainly equip them with skills to critically analyze the problems around them and come up with creative, realistic, and useful solutions. There are no formal prerequisites for this lesson, and any high school or advanced middle school student can participate in and benefit from it. This lesson and all the activities in it can be completed in a regular 50-minute class. It is useful to have some basic classroom supplies such as paper, pens, pencils, post-its and markers which will come in handy for the in-class activities that include interviewing, brainstorming, and prototyping.