1. The document describes how to construct a model of the lungs using plastic bags, tubes, and a plastic jug to demonstrate how lungs contract and expand through breathing. 2. When the rubber sheet covering the jug is pressed, it simulates exhalation by pushing air out of the plastic bag "lungs" through the tube. Releasing the pressure simulates inhalation as the lungs expand again. 3. The model demonstrates how the diaphragm and pressure changes cause the lungs to contract and expand to inhale and exhale oxygen through the windpipe during respiration.

1. Prepared by: Sabita k.c. Submitted to: Anil Sir

17. Prepared by: Sabita k.c. Helped by: Rajesh k.c.