This document discusses electrocardiograms (ECGs), including how to properly record and evaluate them and how to diagnose cardiac conditions with the help of ECGs along with clinical findings. It provides guidance on evaluating features of ECGs like rates, intervals, axes, and rhythms. It emphasizes that ECGs should not be used alone for diagnosis and must be considered together with a patient's clinical presentation and history. It also presents several case studies of pediatric cardiac patients and asks the reader to make a diagnosis based on the ECG and clinical findings provided.