The trainer simulates a sudden cardiac arrest rescue scenario using the same form factor, LCD display, voice prompts, and step sequence that students would encounter on the real ZOLL AED 3. When the trainee opens the device, the trainer powers on and begins the voice-prompt sequence. The trainee attaches the CPR Uni-padz training harness to a CPR manikin; contact sensors in the pads detect proper placement and advance the scenario automatically. During the CPR phase, the trainer measures actual compression depth and rate via sensors in the harness and provides Real CPR Help prompts ("Push Harder," "Good Compressions"). When the trainer prompts for a shock, the trainee presses the (simulated) shock button. The trainer does NOT deliver any electric shock; it only plays the voice prompt and visual indicator. The on-device pause button lets the instructor halt the scenario for teaching at any point.