The lecture discusses measurement system behavior and modeling. It aims to understand how systems respond to different input signals and how instruments modify measurements. Models of zero-order, first-order, and second-order systems are presented. A first-order model is developed to simulate a thermometer's temperature response over time. Second-order systems can oscillate at their natural frequency depending on damping. Characterizing system order, time constants, damping, and frequency response allows predicting instrument behavior.