An electrocardiogram (ECG or EKG) records the electrical activity of the heart over time through electrodes placed on the skin. It shows five main components - P wave, QRS complex, and T wave - that represent the spread of electrical impulses through the heart during each heartbeat. Doctors can analyze features of the EKG like interval durations and waveform shapes to detect abnormalities and disorders of the heart's rhythm or muscle tissue. In this experiment, students will record their own EKG, identify the components, calculate heart rate, and observe how the tracing changes when the electrode leads are switched to simulate a myocardial infarction.