1. Take a bottle with a lid.
2. Make two holes in the lid and insert two straws through them.
3. Fill the bottle with water and close its mouth with the lid along with straws.
4. Adjust the straws such that one should be till the bottom of the bottle and other till the surface of the water.
5. Now blow air with force through the straw placed above the water surface of water.
6. As this blowing air put pressure on water, it escapes out through the second straw.
7. The hight of the water raises through the second straw or the empty space formed in the bottle indicates your lung power.
