Gas exchange

Gas exchange is when we breathe in oxygen and breathe out carbon dioxide. Think of it like a game of catch, where oxygen is the ball that you catch and carbon dioxide is the ball that you throw. When we breathe in, we take in oxygen through our noses and mouth. This oxygen goes into our lungs, where it is exchanged for carbon dioxide. The carbon dioxide is then breathed out of our mouths and noses. It's kind of like breathing out a big, old yawn - but instead of just air, we're getting rid of the carbon dioxide that we don't need anymore. Our bodies are like factories, and they need oxygen to work properly. Without it, we get tired and sleepy. That's why it's really important to breathe in good, clean air - especially if we're running around or exercising.