The Air All Around Us - First Grade Science
Although you cannot see it with your eyes, you are completely surrounded by an invisible ocean of gas called air. Air fills every room, surrounds every tree, blankets the highest mountain peaks, and wraps our entire planet in a protective bubble called the atmosphere. Every breath you take draws fresh air into your lungs to keep you alive. Air can push sailboats across lakes, lift giant airplanes into the sky, support soaring eagles, and spin towering windmills. By exploring air, you uncover the invisible forces that shape our everyday world.
What is Air Made Of?
Air may look like empty space, but it is actually real matter made of microscopic particles called gas molecules. Matter is anything that has mass and takes up space.
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| THE INGREDIENTS OF AIR |
| |
| NITROGEN (78%) The most abundant gas; helps plants grow. |
| OXYGEN (21%) The vital gas humans and animals breathe. |
| OTHER GASES (1%) Carbon dioxide, argon, and water vapor. |
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Oxygen: The Breath of Life
When you inhale, your lungs absorb oxygen gas from the air. Oxygen is carried by red blood cells to every organ and muscle in your body to produce energy.
Carbon Dioxide: The Plant Fuel
Air contains a small amount of carbon dioxide gas. Plants absorb carbon dioxide through tiny pores on their leaves, combining it with water and sunlight to make food and releasing clean oxygen back into the air.
Proving That Air is Real Matter
Because air is invisible, it is easy to forget that it is really there. However, simple experiments prove that air takes up space and has weight!
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| EXPERIMENT: AIR TAKES UP SPACE |
| |
| 1. Take an empty plastic cup with a dry tissue crumpled inside at |
| the very bottom. |
| 2. Turn the cup upside down and push it straight down into a bucket |
| full of water. |
| 3. Pull the cup straight out and check the tissue. |
| |
| RESULT: The tissue is completely dry! The cup was filled with air, |
| and the air prevented the water from entering the cup! |
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Air Has Weight
If you hang two inflated balloons from opposite ends of a balanced wooden ruler, the ruler stays level. But if you pop one balloon, the pan with the inflated balloon dips down immediately! The air trapped inside the inflated balloon has measurable mass and weight.
Moving Air: What is Wind?
Wind is simply air in motion. You cannot see the air itself, but you can see what moving air does to objects around you.
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| EVIDENCE OF MOVING AIR |
| |
| GENTLE BREEZE Rustles tree leaves, ripples water puddles. |
| MODERATE WIND Blows paper along the sidewalk, flaps flags. |
| STRONG GALE Bends tree trunks, makes walking difficult. |
| STORM / TORNADO Lifts roofs, knocks down power lines and trees. |
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What Causes Wind?
Wind is created by the sun! The sun heats different parts of the Earth unevenly. Land warms up faster than oceans, and the equator is much warmer than the icy poles. Warm air expands, becomes lighter, and rises upward into the sky. Cool, heavy air rushes in beneath it to take its place. This rushing motion of air across the ground is what we feel as wind.
The Atmosphere: Earth's Protective Blanket
The blanket of air wrapping our planet is called the atmosphere. It extends dozens of miles up into space and performs vital protective duties.
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| DUTIES OF EARTH'S ATMOSPHERE |
| |
| - SHIELDS FROM METEORS: Burns up falling space rocks before ground. |
| - TRAPS COZY WARMTH: Acts like a greenhouse so nights aren't frozen.|
| - BLOCKS HARMFUL RAYS: Ozone layer filters dangerous sun radiation. |
| - CARRIES WEATHER: Holds clouds, rain, snow, and moisture cycles. |
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Chapter Review Exercises
Question 1: What is air, and what are the two main gases that make up most of Earth's atmosphere?
Question 2: Describe an experiment that proves invisible air takes up physical space.
Question 3: What causes wind to blow across the surface of the Earth?
Question 4: Name two ways that Earth's blanket of air (the atmosphere) protects living organisms.
Solutions and Explanations
Solution 1: Air is a mixture of invisible gases that surrounds the Earth and has mass and takes up space. The two main gases in air are nitrogen (about 78 percent) and oxygen (about 21 percent).
Solution 2: Push an upside-down drinking cup with a dry tissue crumpled in its base straight down into a bucket of water. When pulled out, the tissue remains completely dry because the trapped air occupied the space inside the cup, blocking the water from entering.
Solution 3: Wind is caused by the sun heating the Earth unevenly. Warm air expands and rises, and cooler, denser air rushes in along the ground to take its place, creating the moving current of air we call wind.
Solution 4: Two ways the atmosphere protects life are by filtering out dangerous ultraviolet radiation from the sun (using the ozone layer) and burning up incoming space debris and meteors through friction before they strike the ground.