Describing structure and function of lungs

Objectives:
To develop the skill of model making and describing.

Materials required:
2 Liter water bottle with cap, 2-3 straws, polythene cover, two balloons, scissors, thread, glue, knife.

Pre-requisites:
Meaning of inhalation and exhalation

Process:
Give students the following instructions:


 * Take a 2 liter water bottle; cut 3/4th the bottle as shown in  the figure.
 * Take a long straw, bend 1/4th of the straw, cut small portion  of the straw at the bent surface and attach a small piece of other   straw to the cut portion and stick it using a gum to make a Y-tube.
 * Tie two balloons to both the ends of the Y-tube using a thread.
 * Make a hole in the cap of the bottle and insert a Y-tube with balloons  into it. Now, place it in the bottle by turning the cap
 * Cover the bottom of the bottle using a transparent polythene cover.  (Note-Bottle should not be covered tightly).
 * Model of lungs is now ready. Pull the transparent cover downwards you will  see the balloons inflating, when you release the cover you see the   balloons deflating.
 * Describe the structure and function of the lungs using the model created.

Pedagogic principles:
Describe a life process using the model created.