A Muscle-Computer Interface (muCI) is a human-machine system that uses electromyographic (EMG) signals to communicate with a computer. Surface EMG (sEMG) signals are currently used to command robotic devices, such as robotic arms and hands, and mobile robots, such as wheelchairs. These signals reflect the motor intention of a user before the actual movement. In this article, the authors describe the design and construction of a simple, low-cost muCI as a didactic tool to help students understand electrophysiological concepts. The presentation was designed in a friendly format consisting of a theoretical explanation and a practical demonstration. The theoretical part was provided by the physiology teacher. Students had a short explanation about muscle physiology, the motor unit, and EMG signals. In the practical demonstration, students learned how a simple muCI works and used the muCI to control a robot using their own muscle contractions.