Buzz
Kids are naturally curious and ask a lot of questions.
mental_floss provides answers. This week marks the launch of WHY?, our brand-new series designed for kids and parents. We'll explore the various questions children have about how the world functions, offering science-based, kid-friendly explanations. Though our answers are written for early readers (ages 4 to 7), we believe they’re engaging—and educational—for everyone.
Air is all around us on Earth’s surface. It’s a mixture of gases: 78% nitrogen, 21% oxygen, 1% argon, a trace of carbon dioxide, and tiny amounts of 13 other gases. Additionally, air holds water vapor, which is a combination of hydrogen and oxygen. Air is the layer of the atmosphere closest to Earth. Just like a large protective blanket, the atmosphere prevents us from getting too hot from the sun or too cold from space—and it allows us to breathe.
Land animals cannot survive without the oxygen found in the air. Over 2.3 billion years ago, the atmosphere was primarily made up of nitrogen. Then, tiny microorganisms known as cyanobacteria (SIGH-an-oh-back-TEER-e-uh) began to thrive. Cyanobacteria harness sunlight to convert carbon dioxide into food through a process called photosynthesis. The byproduct of photosynthesis is oxygen. The abundance of oxygen gradually filled the atmosphere, and over time, more animals evolved to be aerobic (air-OH-bick), meaning they require oxygen to live—just like us.
Because plants photosynthesize! Remember, oxygen is a byproduct of photosynthesis, and it's a crucial part of the air. Without oxygen, we wouldn’t be able to breathe. Thanks for producing oxygen, plants! But we help plants too. We breathe out carbon dioxide, which plants turn into food. So plants and animals collaborate to keep every living thing thriving. Isn’t that amazing?
If you're curious to learn more about photosynthesis, check out this gardening guide for kids from the BBC.
