The Four Properties of Matter

Look around you. Everything you see is made of matter. The chair you are sitting in, a table, a houseplant, the air you breathe – all of these things are made of matter. But, what exactly is matter? What is Matter? Matter is anything that is made of atoms. Atoms are the smallest unit of matter, and atoms themselves are made of subatomic particles – protons, neutrons, and electrons. Matter can take the form of a solid, liquid, or gas. This all depends on how closely the atoms in matter are packed together. In a solid, the atoms are locked

Buoyancy Will Float Your Boat

Imagine you are fishing at a lake. You attach your hook to a sinker – a small round ball of metal – that helps it sink to the bottom. While waiting for a fish to bite, you notice a man in the middle of the lake in a small metal canoe. Your sinker and his canoe are both made of metal. Yet, your sinker went straight to the bottom while his canoe held him safely above the surface. How is this possible? What does it take to make a boat float? When you put something into water, the water itself

Friction is a Drag

Friction is a force that creates resistance to movement between two surfaces that are touching. Have you ever gotten “rug burn” as you tried to slide across a carpet? Carpets create a lot of friction. Remember a time you went on a “slip-n-slide.” Did you get scraped at all? Probably not. This is because a slip-n-slide creates almost no friction when it is wet. There are two basic types of friction: static friction and kinetic friction. Let’s take a look at each type: Static friction Static friction is a force that operates on surfaces that aren’t in motion. For example,

Newton’s Laws of Motion

Every now and again, someone comes along who thinks outside the box and changes the way we understand our world. Sir Isaac Newton was one of those people. Sir Isaac Newton Isaac Newton was born in 1642 in England. He worked as a mathematics professor at the University of Cambridge, but he also studied and wrote about physics and astronomy. In 1687, Newton published Mathematical Principles of Natural Philosophy. This book explained the three laws of motion. Let’s take a look at the laws that Newton uncovered! The Law of Inertia The Law of Inertia says that an object in

Speed, Velocity, and Acceleration

Speed, velocity, and acceleration are properties that describe the motion of an object. While these measurements are related, they are different in some important ways. Speed Speed measures distance over time. If you know that a object is moving at twenty miles per hour, you know its speed but you don’t know which direction the car is traveling. Velocity Like speed, velocity tells us how fast an object is moving. In addition velocity tells us which direction an object is headed. You need to know where an object started and ended to calculate velocity. Speed and velocity are sometimes used

What Are Waves?

You may have seen a wave tumbling sand at the beach, or a wave in a pond after you toss a pebble into it. But did you know that waves are actually much more common than the ones you see in water? Scientists have shown that there are light waves, sound waves, ocean waves, radiation waves, and many, many more kinds of waves. You might wonder, if there are so many different types of waves, what exactly is a wave? A wave is a movement of energy through a medium. For waves in an ocean, a lake, or your neighborhood

The Origin of Planet Earth

How Did The Earth Form? To find out, let’s spin back in time—way back. There was no earth or sun or moon. Our solar system – our sun and the eight planets that rotate around it – didn’t exist at all. There was just a big solar nebula. A nebular is a huge cosmic cloud of gas and dust. Then, about 4.6 years billion years ago, some of that dust and gas pulled together into a fiery ball. That became our sun. The rest of the dust and gas from the solar nebula clumped into planets. One of those planets

Life on Earth

Where did Earth’s water come from? That’s an important question, because after all, Earth is a very watery planet. There’s a reason it’s called the Blue Planet! And without water there would be no life…and no us. Water is also essential to life on earth and covers most of our planet. Scientists think that much of Earth’s water arrived the hard way, by crashing into the planet’s surface inside icy meteorites during those first million or two years. There is also evidence that a lot of water may have come from within the solar nebula itself. That means a lot

The Sun

Thank goodness for the sun! Life couldn’t exist on Earth without it. There are lots of reasons why. For one thing, the sun’s heat keeps Earth from being an unlivable ball of ice. What exactly is the sun? What are some of the ways our world depends on it? And how does it sustain life? Star of the Show Our solar system just has one sun. Some solar systems have two or more! But one sun is all we need. Not only is our sun the star of the show here on Earth, it’s actually a real star. Although our


The reason for our seasons Like all planets, Earth orbits its sun. It takes 365.25 days for Earth to make one complete trip around our sun. That’s what we call a year, of course. Every four years, we add an extra day, called Leap Day, to catch up with the extra quarter days. At the same time that Earth is circling the sun, it is also rotating on its axis. The axis is a line from the north to the south pole, through the center of the earth. Each rotation is a day. So when you watch the sun “rise,”

The Origin of the Moon

Where did the moon come from? Although some planets have many moons, Earth has just one. Our moon is about one quarter the size of Earth. Scientists estimate that the moon is just a little younger than Earth, about 4.51 billion years old compared to 4.54 billion years for Earth. In fact, what we know about the moon suggests that it is made of material that broke off from Earth when a huge object—some say a planet—crashed into our planet when it was very young. The impact destroyed the object and also knocked a huge amount of material from Earth

Lunar Cycles

Like all moons, Earth’s moon orbits its planet. Sometimes we see a full moon. Other times only a small crescent. And for a night or two each month, we see no moon at all. How much moon we see from Earth depends on where the moon is in relation to the sun and the earth. As the crescent of the moon grows bigger, we call that a waxing moon. After the full moon, the surface that we can see grows smaller. This is called a waning moon. When the moon is dark from Earth’s view it is called a new

Our Solar System

Imagine travelling at 67,000 miles per hour. Guess what? You are! That’s how fast Earth spins around the sun. Earth isn’t alone of course. We’re just one speedy little planet in a whole solar system. Put simply, a solar system is a collection of objects that orbit a star or sun. Along with Earth, our solar system includes seven other planets. There are also dwarf planets like Pluto, which are smaller than normal planets but still directly orbit the sun, and are nearly round. There are also at least 150 assorted moons, which orbit planets, along with millions of smaller,


When you jump up, you come back down to earth again. Did you ever wonder why you don’t float off into space? The answer is gravity. The Earth’s gravitational force pulls you down so you don’t go up and up forever. What is gravity? Gravity is a force of nature that pulls objects together. The Earth’s gravity pulls you toward the ground. The Earth’s gravity also pulls on the moon. Gravity is what makes the moon orbit around the Earth. Your body has gravity, too. But, because you are much smaller than a planet, your gravitational force is much smaller.

Plate Tectonics

How are you at puzzles? Did you know you are living on one? Earth’s crust-the thin, brittle surface of the planet is broken up into pieces like a giant jigsaw puzzle. There are about 20 or so of these pieces. The pieces are called tectonic plates. Every part of Earth’s surface, oceans and continents alike, rides on a tectonic plate. And…Action! The big thing about tectonic plates is that they move. That motion is slow, on average maybe an inch per year. But it adds up. If a plate moves just one inch each year, that’s about 15 miles every


Earthquakes can rock your world – literally. At least a million earthquakes occur worldwide every year. Most of them are so small only very sensitive instruments can detect them. About 12,000 to 14,000 earthquakes each year are big enough for people to feel. Even most of those don’t cause real damage. But the biggest earthquakes are incredibly powerful. They can cause entire buildings to shake into pieces, trigger tsunamis and landslides, and shift the land surface. Moment magnitude scale Clearly, earthquakes come in all sizes. To describe their intensity, seismologists—scientists who study earthquakes—use a special scale called the moment magnitude

Seismic Waves

Learning from Earthquakes When an earthquake lets loose, it sends ripples of energy through Earth called seismic waves. There are two main types of seismic waves that travel from the site of an earthquake: P waves (for “pressure”) and “S” waves (for “secondary” or “surface”). P waves are faster and therefore arrive first. They are compression waves, moving the ground back and forth sort of like a Slinky. S waves are slower, but can cause much more destruction. They cause the ground to ripple up and down, like shaking a rug. The closer you are to an earthquake, the closer


You probably know something about volcanoes. Maybe you’ve seen a volcano. Maybe you’ve even visited one. But did you know that volcanoes come in many sizes and shapes, and that they have big impacts on our world? Or that once in a while, a new one even pops up unexpectedly. Volcanoes form where melted rock (called magma) from deep underground erupts onto Earth’s surface. Once the magma reaches the surface, it’s called lava. Lava then cools and hardens into volcanic rock. Along with lava, volcanoes can erupt steam, ash, and gases. Where does magma come from? To understand where magma

The Water Cycle

There’s a reason Earth is often called the Blue Planet. Water is nearly everywhere, as liquid, vapor and ice. All this shape-shifting water, whatever form it is in at a given moment, is connected. It constantly moves from one phase and location to another. That perpetual water motion, powered by heat from the sun, is called the water cycle. The water cycle cleans Earth’s water, replenishes it, and transports it from place to place. Not only does the water cycle connect different phases of water, it also connects every living thing. Without the water cycle, life could not exist. The

The Carbon Cycle

We don’t always think about how elements impact our daily lives. But without carbon, we wouldn’t even have life. In fact, carbon is the basis for all life on Earth, a crucial part of our bodies and all plants. We eat and breathe carbon, and use it in many other ways too. Carbon is also a major component of Earth’s atmosphere, oceans, and rocksl. Carbon atoms connect these systems, moving through our world in a continuous cycle called the carbon cycle. As it moves, carbon takes on many forms and bonds with other elements in many ways. Let’s follow the


Glaciers are very large accumulations of ice that slowly flow like rivers. In fact, the definition of a glacier is a river of ice. What can make ice flow? Lots and lots of snow, combined with time. Glaciers form when more snow accumulates in winter than melts in summer. Over years of accumulating snow, the weight of all that snow presses deeper layers of fluffy snow into dense ice. It takes around 200 feet of built-up snow to begin to form a glacier. Because the ice is so dense, most of the air bubbles you would find in regular white

Climate Change

You probably hear a lot about climate change these days. What is it, and what does it mean for Earth’s future… and for you? Earth’s climate has experienced plenty of ups and downs before. There have been Ice Ages, when much of the planet was covered in ice. There have been warm periods, too. These changes in climate occurred because of natural processes. They took place gradually, over hundreds or thousands of years. But the current change in Earth’s climate is different. It is happening more quickly than other times. And we know that it is caused by human activity.

What is an Ecosystem?

Think of a farm. Rain falls, organisms in the ground produce nutrients and the farmer gets to eat the delicious fruits and vegetables the farm produces – this is an ecosystem. An ecosystem is a group of plants and animals that live in the same place and continuously interact with each other. It can include plants, animals, and microorganisms, as well as many non-living elements like rain, sunshine, and minerals in the soil. There are two basic types of ecosystems: terrestrial and aquatic. Terrestrial ecosystems are based on land. Aquatic ecosystems are found in ponds, lakes, streams, oceans, and other

The Human Digestive System

NOM, NOM, NOM! Lunch sure was delicious! But, do you know what happens to food once it enters your body? The human body can do a lot of amazing things. One of the coolest things it can do is digest food into energy. After you take a bite of food, your teeth work to grind it up. You swallow, and it travels into your stomach. Strong acids and other chemicals slowly break it down into smaller and smaller pieces. The food is passed into your small intestine, which pulls out the nutrients it needs to make you strong and give

What’s In A Cell?

Every living thing in the world is made up of cells. Cells are the building blocks of life. There are two basic cell types: prokaryotic and eukaryotic. Prokaryotic Cells When life first emerged on earth, it was made up of very simple organisms called prokaryotic cells. Though life evolved to be more complex, many organisms are still prokaryotic. For instance, there are trillions of bacteria that live in your small intestine that are still prokaryotic. Eukaryotic Cells Complex organisms need their cells to do many things. Some of these things are only possible inside of organelles. Organelles are inside cells

The Mysterious Human Body

You probably don’t realize it, but as you are reading this your body is doing amazing things! Energy from the food you ate for breakfast is currently powering your brain. Your brain is tracking the screen and telling your hand when to keep scrolling. The muscles in your hand need oxygen to work. Your heart is constantly beating to carry oxygen to your hand and brain, so they can continue working. Don’t forget about your lungs that collect oxygen, your stomach that had to digest your food, your intestines that absorbed nutrients, and all the other organs in your body

Why Biodiversity Matters

Planet Earth is currently home to about 10 million species of plants, animals, fungi, bacteria, and other living things. That’s just an estimate: scientists have only named and classified about two million of those species. All these species, large and small, work with other species to create thriving ecosystems. Healthy ecosystems provide ecosystem services. These services include clean drinking water, the food we eat, the wood we use to build our homes, medicines, and much more. Preserving biodiversity helps keep ecosystems healthy and healthy ecosystems help humans thrive! What is Biodiversity? Biodiversity is the amount and variety of life in

The Classification Of Plants And Animals

Scientists classify all living organisms into different groups and subgroups. This is called taxonomy. Carl Linnaeus, a botanist in Sweden, developed the modern classification system of taxonomy. The classification system is a structure that groups organisms into more and more specific groups. Domain Domains distinguish between organisms at the cellular level. This first level separates life based on their cell type. Eukaryotic cells are made up of even tinier parts, called organelles and can form complex organisms – like humans! Prokaryotic cells are very simple and do not have cellular organelles. Kingdom A kingdom is a very big umbrella that

What Is A Pandemic?

A pandemic happens when a disease spreads across several countries at the same time. Pandemics can be challenging to deal with because doctors cannot treat all the sick people at once. How do Diseases Spread? Diseases that affect the respiratory tract can spread through water droplets. When you breathe, talk, or chew with your mouth open, you are constantly releasing millions of tiny water droplets. When you cough or sneeze, you shoot these tiny droplets into the air. Some of the droplets are heavy and drop to the ground quickly. Other droplets are very small particles that can hang in

Photosynthesis: The Original Green Energy

Plants and algae can do something that you can’t do: they make their own food! Using photosynthesis, plants make complex food molecules that give us energy. In the process, they also make oxygen. Every time you eat fruits or vegetables, or even meat or dairy, you are also consuming energy that was first captured by plants. The Ingredients for Photosynthesis Plants make their own food molecules – sugars called glucose – by absorbing light and combining molecules from the air and from water. The three ingredients plants need for photosynthesis are sunlight, carbon dioxide and water. Plants get the carbon

Evolution: Life On The Move

Species are constantly changing. They must continuously adapt to the changing world around them. Animals that are successful can reproduce more, and their babies go on to have more babies. This is Evolution. Natural Selection Humans have known that plants and animals could change for a long time. Ancient farmers bred better crops by taking seeds from the best plants in each season and replanting them. Humans selected the best hunting dogs for breeding. It was not until Charles Darwin traveled the world, on a research ship known as The Beagle that the Theory of Evolution was well understood. Darwin

How Plants Reproduce

Imagine being stuck in the ground, with no ability to move your body. That is essentially the life that plants live. So, how do plants manage to reproduce? Plants have developed many different ways to reproduce. They use seeds, roots, spores, cuttings, and clones to create new plants. Some plants reproduce on their own and others need help from pollinators like bees and birds. There are two types of reproduction in plants: sexual and asexual. Sexual reproduction requires male genetic material and female genetic material to create a new plant. Asexual reproduction does not. Let’s take a look at both

What Fossils Tell Us About Life On Earth

A fossil is a record of a plant or animal that lived thousands or even millions of years ago. Some fossils are very big, like dinosaur bones. Others are so tiny you need a microscope to see them. The scientists who dig for fossils and study them are called paleontologists. How do fossils form? Fossils are usually impressions of hard structures like wood, bones, or shells that don’t decompose quickly. Typically, fossils form when a dead organism gets covered in sand, mud, or clay. Over time, minerals from the soil surrounding a dead animal slowly replace parts of the animal.