Follow the path that air takes inside your body:
Starting at the top at number "2" and connect the EVEN numbers to see the path where you breathe IN.
Then start at the bottom at number "1" and connect the ODD numbers to find the path where you breathe OUT!
The graphic shows a picture of air entering into the body through the nose, and traveling into the lungs.
The blue line is oxygen going in, and the yellow line is carbon dioxide going out