Many of us have experienced that existential “wow, science!” moment in adulthood.
It may have occurred while watching an ice cube melt in the sun. Suddenly, it dawns on us that the ice is actually made of crystalline water molecules, that they are absorbing light from a star 93 million miles away, and that it’s causing them to wiggle excitedly until they slide off the ice cube. The colossus of scientific knowledge behind even this simple process can be overwhelming, provided it catches us in the right mood.
But here’s the tougher question — how do you translate this wonder to children in a way that inspires and engages them?
Science is fascinating, fun and extremely useful in children’s futures. Most importantly, understanding its principles allows them to engage with the world around them by thinking critically about everything they see — literally, everything they see. Why are puddles of water frozen in the morning? Why does boiling water create steam? Why is there steam-like mist hovering over riverbeds in the morning?
Let’s take a look at the best ways to teach children about states of matter, one of the most applicable and ever-present scientific concepts in their lives.
Start With the Building Blocks of Matter
One of the greatest parts about this subject is that nature has put it on display for us everywhere we look. States of matter start with atoms and molecules.
An atom is the basic building block of nature. This is a particle 1 million times smaller than a speck of dust, meaning it is impossible to see it. You can drive the small size of an atom home by asking children how many atoms they think are in a single grain of salt. The answer is 1,200,000,000,000,000,000 — that’s 1.2 quintillion.
A molecule, on the other hand, is what results when two or more atoms bond together. This small cluster of atoms forms a new substance altogether. For instance, while gold is made up of individual atoms packed together, water is made of molecules. Specifically, water is made of two hydrogen atoms bonded to a single oxygen atom.
Atoms and molecules often bond to one another, meaning they have attractive forces between them that cause them to stick together. This is why water forms beads instead of spreading apart.
There are loads of fun facts about atoms. If you’re looking for ways to instill a sense of wonder into children about atoms and molecules, sprinkle these facts into your conversations:
- Atoms are made up of 2 parts: the nucleus, made of protons and neutrons, and electrons that orbit it. Though it’s actually quite a bit more complicated, you can illustrate by comparing it to planets orbiting the sun.
- Most of an atom is empty space. If one atom were the size of a football stadium, the nucleus would be right in the center of the field and would be the size of a pea. That means the solid thickness of everything around you is an illusion — it’s mostly empty space.
- If an atom were bigger — say, if it were the size of a period at the end of a sentence — then a human lying on their back would stretch from Dallas, Texas to Los Angeles, California.
- “Atom” is derived from the ancient Greek term for “uncuttable.” The Greeks supposed that one could take a piece of matter and keep cutting the pieces in half until it was impossible to make them any smaller. This smallest piece was what they called the “atom.”
- There are about 7 billion billion billion atoms in your body. Through eating, drinking and breathing, you replace 98% of these atoms every year.
- If a child is having trouble understanding what a billion is, show them a visual representation of 7 billion people. This is the approximate population of earth and gives an idea of how large these numbers are.
The States of Matter
Technically there are 5 states of matter, but most people only need to know 3. Here they are:
A material in solid state holds its form and shape. That means it doesn’t flow. Solids can be many different colors, can have different hardness and come in a variety of shapes. Just because an object is solid doesn’t mean it can’t be squished or molded — it means that, if left untouched, the material won’t flow.
Examples of solid objects include:
There are many solids that can be compressed and molded, such as clay, Play-Doh, cushions, fabric and clothing. Even though this latter group changes shape when we poke and squeeze it, this doesn’t mean it isn’t a solid. If you left it sitting on a table in a moderately cool room, it would have the same shape when you came back to it later as when you left it.
Let’s think about how this relates to atoms and molecules. In a solid, atoms and molecules huddle closely together, which makes them rigid and stiff. This effectively means they are frozen in place and do not flow around one another. This stiffness occurs because the bonds between the atoms or molecules are strong and hold them together.
A liquid takes the shape of its container. That means if you pour it into a bowl, it will fill the bowl from the lowest points upward and come to rest. Imagine the difference between placing a large chunk of ice into a bowl versus pouring the same amount of water into it. The ice is solid and will keep its shape, while the water will fill the bowl.
Liquids can have different thicknesses, known as “viscosity.” For example, pancake batter is thicker — it is more viscous— than water and flows more slowly. Examples of liquids are:
Mercury is an example of a metal that is also a liquid.
To better understand viscosity, picture yourself waking up on a cold morning. You don’t exactly throw the covers off and jump out of bed. Rather, you pull the covers farther up and are slow to get moving. Many liquids react to cold the same way — the colder they are, the slower they move. This is the case for substances like syrup, oil and liquid bath soap. Note that water does not react the same way, but as we shall see, water is one weird substance.
The atoms and molecules in liquids are farther apart than in solids, which gives them the freedom to move around and lessen the bond between the individual atoms. In the liquid state, atoms and molecules are far enough apart to flow around one another but not so far as to be in the final state of matter — a gas.
A gas is a substance that behaves like the air around us. Gases also take the shape of their container, but they are much lighter than liquids. That means they will expand to fill any container they are placed in. If you poured water into a glass fish bowl, the water would fill the container from the bottom up. If you did the same with gas, it would expand to fill every part of the glass fish bowl, not just the bottom.
It is not hard to move through gases, and if they escape their container, they will quickly spread through the surrounding air. You can’t measure how much gas there is using a scale or a measuring cup. To figure this out, you have to use math. Examples of gases include:
- Steam from boiling water
- Smoke from smokestacks
- Exhaust from cars
Within a gas, atoms and molecules are far apart from one another and bounce around independently. They do not flow around one another as in a liquid, but rather ping off each other freely in all directions.
Changing States and Temperature
Now that we have covered the 3 states of matter, it’s time to discuss a phenomenon that we can see in everyday life. This is the changing of states, or the tendency of matter to shift between solid, liquid and gas.
We see this all the time — butter melting on hot toast, ice melting to form water, water boiling to form steam, beads of water condensing on cold surfaces or sweat evaporating. In our everyday experience, the most common reason formatter to change states is temperature. A material in solid form is colder than the same material in liquid form, which is colder than its gaseous form.
Let’s look at some of the changes that occur between the states of matter.
1. Changes Between Solid and Liquid States
To understand the shift between solid and liquid states, it’s helpful to try a very delicious example for yourself: butter melting on a piece of hot toast. Butter is quite hard when it comes out of the refrigerator. When you place a chunk of it on a piece of toast fresh out of the toaster, however, it begins to soften up and turn to liquid, making it easier to spread.
Let’s zoom in now on the atoms and molecules making up butter. When they come out of the refrigerator, they are huddled close together and are cold and rigid. Then, a giant knife slides in and whisks a whole section of them away, only to plop them onto a hot piece of bread. The heat from this bread spreads into the butter. It disperses among the molecules, warming them up and causing them to move apart from their neighbors.
Eventually, they are far enough away from each other that they can begin to flow around one another. Zooming out, this is the liquid stage of butter. Because the cold butter absorbed more energy in the form of heat, its molecules began wiggling around and were freer to move.
Before we move on, let’s look at the reverse process with a liquid-to-solid experiment. Picture a bowl of melted butter placed in the fridge. We know that the butter molecules are freely flowing around one another in liquid form because they have enough heat to do so. But as the butter’s heat gets sucked away by the freezer, the molecules within it begin to huddle together and slow down. Eventually, they will congeal and form a solid.
2. Changes Between Liquid and Gaseous States
Teaching kids about the state of matter is easier when you have something for them to look at. Try using a liquid-to-gas experiment to illustrate this change.
Boil a pot of water on the stove. You turn up the dial and begin to heat it up. This heat passes into the water through the bottom of the pot, and, in response, the water molecules start to move around. More and more heat is added. They move around more and more in response. But how long can this go on? Will they just keep moving faster and faster?
At a certain point, the water molecules absorb enough heat energy that they turn into a gas. This means they move so rapidly, they rise to the top of the water and escape into the surrounding air. From our vantage point outside, this is steam rising from the pot of water. This process eventually leads to evaporation.
The reverse of evaporation is condensation. There is water in the air around you at all times. It has evaporated off of rivers, lakes and oceans and out of the soil and is a large part of our atmosphere. These water molecules are in gas form, and even though they are not at boiling temperature, they are light enough and far enough apart that there is no reason for them to turn liquid again.
However, imagine now that you’ve got a cold glass of iced lemonade. The moist air around the glass, which contains water, comes in contact with the cold glass. The cold causes the gaseous water in the air to “condense” — that is, it collects on the glass because the heat has been sucked out of it, until there is enough of it to form liquid water. This liquid water collects and forms the drips and drops we all recognize as condensation.
Water: One Weird Substance
It is worth noting that water, the most important liquid in our lives, is also probably the strangest substance we know of. Scientists regularly scratch their heads at its bizarre tendency to break all the rules. Here are some of the strange facts about water you may want to mention when explaining states of matter to kids:
- It expands when cold. It is a basic universal rule that substances contract, or shrink, as they get colder. That’s why we’ve been doing all this talk of atoms and molecules “huddling” together when they lose their heat. But water expands when it freezes. For example, ice frozen in a glass will produce a seemingly smaller amount of water in the glass when it melts.
- It takes a lot of energy to heat it up. Water can absorb a lot of heat before turning to a gas — kind of like a boxer who can take a lot of blows before losing the match.
- It can dissolve almost anything. For being such a nourishing part of life, water sure does tend to tear things apart. It can dissolve sugar, salt and many other solids — more than any other liquid known to man.
Let Science Explorers Awaken a Child’s Inner Scientist
Bolstering your child’s science education can open new doors for them and help them understand the world. Science Explorers offers fun summer camps and afterschool clubs that let children explore and interact with the world around them. This leads to greater motivation, understanding, performance in school and general interest in their surrounding environment.
Our life’s work is to make science fun for kids. In the words of our owner and founder, Jupiter Jen, “If it’s not fun, we’re not doing it.” This program is perfect for children ages 4-11, allowing them to become engaged with science and remove its stigma as a tough subject. We focus on a hands-on format with cool experiments like dissections, chemistry, creating cool materials, looking at organs, launching rockets and much more. Get in touch today to learn more about our programs.