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An introduction to the concept that everything around us is made of matter and takes up space.
Look around you. Everything you see—from your heavy backpack to the invisible air you breathe—is made of the same 'stuff.' But what exactly is that stuff, and how do we know it's there even when we can't see it?
In science, we call the 'stuff' that makes up the universe matter. To be matter, something must follow two very important rules. First, it must have mass, which means it has weight and can be measured on a scale. Second, it must take up space, which we call volume.
Think of your favorite toy. It has weight when you pick it up, and it takes up a spot on your shelf. Because it follows both rules, your toy is matter! Even the smallest grain of sand is matter because it takes up a tiny bit of space and has a tiny bit of weight. If you can touch it, taste it, or weigh it, it is definitely matter.
Let's see if a school book is matter: 1. Does it have weight? Yes, if you put it on a scale, it might weigh pound. 2. Does it take up space? Yes, if you put it in your backpack, there is less room for other things. Conclusion: The book is matter!
Quick Check
What are the two 'rules' something must follow to be called matter?
Answer
It must have mass (weight) and take up space (volume).
Some matter is easy to see, like a chair or a glass of juice. But what about air? You can't see it, and it feels like nothing is there. However, scientists have proven that air is matter!
When you blow into a balloon, the balloon gets bigger. This happens because the air is moving inside and pushing the sides out. The air is taking up space. Also, if you weighed an empty balloon and then weighed a balloon full of air on a very sensitive scale, the full one would be slightly heavier. Even though it is invisible, air has mass and takes up space, so it is matter.
Imagine a flat soccer ball. 1. When you use a pump, you force air into the ball. 2. The ball changes from flat to round. This proves the air is taking up space inside. 3. The ball feels 'tighter' and slightly heavier. This proves the air has mass.
Quick Check
If you blow air into a plastic bag and tie it shut, why does the bag stay puffed up?
Answer
Because the air inside is matter and it is taking up space.
Not everything in the world is matter. Some things do not have weight and do not take up any space. These are usually forms of energy. For example, light from a flashlight is not matter. You can't hold light in your hand, and it doesn't weigh anything on a scale.
Heat and sound are also not matter. You can feel heat and hear sound, but they don't take up space in a jar. If you can't weigh it and it doesn't take up room, it isn't matter!
Think about a flashlight shining on a wall. 1. The flashlight itself is made of plastic and metal. It has weight and takes up space. (Flashlight = Matter) 2. The light coming out of it can be seen, but it has no weight and doesn't push things out of the way to make room for itself. (Light = Not Matter)
Which of these is the best definition of matter?
Why is air considered matter?
The heat from a campfire is an example of matter.
Review Tomorrow
In 24 hours, look at three objects in your kitchen and explain to someone why they are matter using the two rules (mass and space).
Practice Activity
Try the 'Glass and Napkin' experiment: Stuff a dry napkin into the bottom of a glass. Turn the glass upside down and push it straight down into a bowl of water. The napkin stays dry! Why? Because the air inside the glass is matter and takes up the space, blocking the water from getting in.