Chapter 22 Fresh Air-Why We Need It.

If you were asked how we can tell that air is everywhere, what could you say?

What do we call a thin light substance like air?

What proof have we that the body needs it? How does it get around to the different parts of the body?

What is the body-its muscle, bone, skin, and all-made up of? How do these cells use the air? Why do you need to