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Students learn that living things need air to breathe, even if they live underwater or deep in the soil.
Take a big, deep breath! You can't see it, smell it, or touch it, but you just took a giant gulp of something your body cannot live without. What is this invisible magic?
Just like you need food and water, every living thing needs air. Air is all around us, even if we can't see it. Inside the air is a special gas called oxygen. Our bodies use oxygen to turn food into energy so we can play, run, and grow. Without air, living things would stop working. Even though you can't grab a handful of air, your body is constantly 'snacking' on it every time you breathe in!
Quick Check
What is the name of the special gas in the air that our bodies need?
Answer
Oxygen
Humans and many land animals have lungs. When you breathe in, your lungs fill up like two balloons. But what about fish? They live underwater! Fish have special parts called gills on the sides of their heads. As water flows over the gills, they pull the tiny bits of air out of the water. It’s like having a built-in filter! Most humans have lungs, while fish can have several gill slits to help them catch enough air.
Let's look at how we breathe compared to a fish: 1. A human opens their mouth or nose and pulls air into lungs. 2. A fish opens its mouth and lets water flow over its gills. 3. Both the human and the fish take the oxygen they need and get rid of the air they don't need.
Quick Check
What do fish use to get air out of the water?
Answer
Gills
You might not see a plant cough or sneeze, but plants need air just as much as you do! Instead of a nose or gills, plants have thousands of tiny, invisible holes on their leaves called stomata. These holes are so small you would need a microscope to see them. Plants 'breathe' in air to help them make their own food from sunlight. If you covered a plant's leaves in thick wax, it wouldn't be able to breathe and would eventually wilt.
Think about an earthworm living deep in the soil. How does it breathe? 1. There are tiny pockets of air hidden between the pieces of dirt. 2. The worm breathes through its skin! 3. If the soil gets too much water (like during a heavy rain), the air pockets disappear, and the worm has to crawl to the surface to find air.
Air isn't just in the sky. It is mixed into the water in the ocean and trapped in the soil under your feet. Every living thing has a unique way to find it. Some whales have a blowhole on top of their heads so they can grab a quick breath at the surface before diving back down. No matter where a living thing lives, it must find a way to get that invisible oxygen!
Imagine a human wants to stay underwater like a fish. 1. Humans have lungs, not gills, so we cannot pull oxygen from water. 2. To solve this, we carry a metal tank filled with big supply of compressed air. 3. We use a tube to move that air from the tank into our lungs so we can breathe while we swim with the fish!
Which of these is a basic need for a living thing?
How do plants get the air they need?
Fish do not need air because they live underwater.
Review Tomorrow
Tomorrow morning, try to remember the two different body parts animals use to breathe: one starts with 'L' and one starts with 'G'.
Practice Activity
Go outside and look at a leaf. Can you see the tiny holes? (Hint: They are too small to see, but imagine them working like little mouths catching the air!)