The document provides instructions for making a lung model using common household items. The model uses a cup with a hole drilled in the bottom to represent the rib cage. A balloon is inserted through the hole and attached to a straw to represent the lungs. A square of plastic sheeting cut from a garbage bag and attached to a strip of tape is used as a diaphragm muscle. Pulling down on the diaphragm causes the balloon to inflate, representing inhalation, while pushing it up deflates the balloon in exhalation. The model demonstrates the basic functioning of lungs and diaphragm.