Teaching Strategies, Tactics, and Methods

An irreversible change is when something cannot be changed back to its original form. In many irreversible changes, new materials and substances are formed.

What Is An Example Of An Irreversible Change?

Burning – Once something is burnt, it can’t be reverted to its original form. Likewise, it can’t become unburnt. So, for example, once a piece of paper has been burnt, it can’t be used to write or read anymore.

Cooking – Cooking changes the chemical composition of a substance. Once eggs or meat become cooked, it will never be raw again. Likewise, once a cake is baked, it won’t ever become milk and flour again.

Rusting – Once Iron is oxidized, it cannot become unrusted. The rusted part can be sanded off, and the underside can be re-shined, but the iron will eventually thin out if this continues.

Mixing – Mixing some substances can cause an irreversible change to create a new substance, for example, cement, vinegar, and bicarbonate of soda, to produce carbon dioxide.

What Is A Reversible Change?

A reversible change is often a physical change that can be reversed. It can include freezing water (which can be thawed back into the water) or melting chocolate (which can then be frozen back into a bar).

Why Is It Essential To Learn About Irreversible Changes?

Irreversible changes happen around us all the time. Children can understand how and why these changes occur and develop scientific knowledge.

Aesop’s Fables is a collection of fables written by ancient enslaved Greek and storyteller Aesop in the 5th century BCE. Aesop and his fables are known to us due to their mentioning by ancient Greek philosophers and historians, such as Herodotus. In addition, tales credited to Aesop have been gathered across the centuries in various languages, such as Greek and Latin.

An observer of animals and people, Aesop’s Fables include talking animals and plants with human characteristics. Aesop’s Fables have a solid moral message at the core. His stories have been taught to children to teach them ethical and moral behavior.

Who was Aesop?

Aesop was an Ancient Greek fabulist and storyteller famous for writing a collection of fables known as Aesop’s Fables.

It isn’t easy to gather information about Aesop’s biography and facts about him. His life is a bit of an enigma, and there isn’t enough concrete evidence to suggest he was even a natural person! Some believe another writer may have just used his name. Despite this mystery, there is mention of Aesop throughout Greece’s history, which has allowed historians to build a somewhat fragmented biography.

It’s believed Aesop lived between 620 and 560 BC, but there are disputing records about where he came from.

Facts about Aesop

While we don’t have a complete picture of Aesop’s life, historians have managed to discover some facts about him:

1. Aesop’s Fables may not be Aesop’s Fables! That’s right, while most historians accept there was most probably a man named Aesop who wrote most of the fables, some scholars argue that he didn’t write a lot of the fables attributed to Aesop. Sumerian proverbs tended to follow the same structure and story of Aesop’s Fables, so much so that it may be the case he didn’t write the sayings.
2. He was an enslaved person who was supposedly let go by his second master because he was so intelligent and witty!
3. It’s theorized that he featured talking animals in his fables because he had difficulty speaking but could speak freely through his anthropomorphized animals.

What are fables?

Fables feature animals, plants, legendary creatures, inanimate objects, or forces of nature that are anthropomorphized (given human qualities). Fables always have an underlying moral lesson learned through reading the story. The importance of fables is not the story itself but the moral learned.

Fables are told to children all around the world. Their simple themes make them easy to understand and help teach valuable life lessons.

Here is a list of Aesop’s Fables:

• The Bear and the Bees
• The Boy Who Cried, Wolf
• The Boys and the Frogs
• The Cat and the Rooster
• The Cat, the Rooster, and the Young Mouse
• The City Mouse and the Country Mouse
• A Council of Mice
• The Dog and His Reflection
• The Nonessential and His Master
• The Fox and the Lion
• The Fox and the Crow
• The Fox and the Mask
• The Frog and the Ox
• The Goose That Laid the Golden Egg
• The Lion and the Mouse
• The Lion’s Share
• The Man and His Two Wives
• The Peacock’s Complaint
• The Rooster and the Fox
• The Rooster and the Jewel
• Sour Grapes
• The Tiger and the Crane
• The Tortoise and the Hare
• Two Men and the Bear
• The Wind and the Sun
• The Wolf and the Crane
• The Wolf and the Goat

Many of Aesop’s Fables have sparked famous sayings that are used today. Some of these include:

• ‘Beauty is only skin deep.’
• ‘Choose the lesser of two evils.’
• ‘Every man for himself.’
• ‘Slow but steady wins the race.’
• ‘Think before you act.’
• ‘You cannot escape your fate.’

Aesop’s Fables – Morals

Every single one of Aesop’s Fables has a moral from which we can learn something. Here, we’ll review some of the most famous fables and their morals.

What Does Flammable Mean?

The word ‘flammable’ applies to any substance, material, or object that burns quickly. While almost every material on earth will burn if it gets hot enough, many objects, like most types of metal, can’t be made hot sufficiently by everyday means of ignition. Flammable materials are particularly vulnerable because of the types of particles that they’re made up of. Fire needs three things to start and to keep burning: heat, fuel, and oxygen (which can be found in the air), which are commonly referred to as the Fire Triangle. Most flammable materials contain carbon particles, which is a perfect fuel for fires because it degrades when exposed to heat. As the material is heated, the carbon ignites and becomes fuel for the fire, spreading further through the material, getting hotter and more prominent as it goes until it is completely consumed.

How can fires be stopped?

If a fire runs out of either fuel or oxygen or is cooled down, it’ll go out, so modern firefighters have developed many techniques for putting out fires that take away one or both of these essential resources. Water reduces the temperature of some fires to a level where the chemical reactions of burning or combustion can’t occur. Fire extinguishers release a directed jet of Carbon Dioxide, helping to lower the Oxygen level in the air around the fire and starving it of the oxygen it needs to burn. Fire blankets work similarly, blocking the fire and preventing it from consuming oxygen in the air outside the veil. However, sometimes the only way to stop a fire is by removing fuel. During the Excellent Fire of London in 1666, the fire was so vast and hot that the only way to stop it was to starve it of more fuel. People used massive hooks to tear down wooden houses in the crowded streets or even used gunpowder to blow up homes in the middle of long rows of houses. Although it seemed like a crazy idea because the fire couldn’t cross the gaps where the homes used to be, it was unable to spread further, and after it had consumed entirely the homes that were already on fire, it had no more fuel and gradually went out. It’s hard to say, but these desperate measures likely prevented the fire from destroying the entire city! m

What’s the Difference Between Flammable and Inflammable?

Contrary to popular opinion, there is no difference between flammable and inflammable. Both words derive from the Latin inflammable, meaning “to cause to catch fire.” Instead of invalidating the subject word as it does in English (insufficient, inadequate), in Latin, the -in prefix means ‘to cause.’ So, rather than the strangers some people take them for, the words flammable and inflammable are non-identical twins.

Objects that are incapable of burning are known as ‘non-flammable.’

10 Examples of Flammable Materials at Home

Although the risk of fires caused by flammable materials at home can be dangerous, we also need them for a wide range of different reasons, from cooking our food to fuelling our cars and lighting up our cities! Here’s a list of some of the most common flammable materials that you can find in and around the home:

• Deodorant – while stick deodorant is relatively stable, spray-on deodorant is highly flammable for a few reasons. First, the can uses compressed gas to disperse the particles of deodorant so all the particles are very close together, making it easy for a fire to spread between them. Secondly, the gas carries thousands of tiny particles – while each particle will burn up extremely fast, there are so many of them that it can still cause a big fire. Finally, most spray-on deodorants have alcohol as an ingredient, so the particles are ideal fuel. Because of this, even a tiny spark near a freshly sprayed cloud of deodorant can set off a massive firey explosion.
• Paper – paper is made up of compressed and dried tree pulp. Wood, the root material, is full of carbon particles, making it an excellent fuel for the fire, and paper has even less water in it to slow the combustion rate, so it’s very explosive.
• Petrol – although this one might seem a little strange, cars run on combustion engines that work by slowing burning petrol in a controlled way to release energy that powers the movement. So not only is petrol extremely flammable, we need it to be!
• Cooking Oil – cooking oil contains a lot of carbon from the seeds or vegetables that were crushed to release the substance, so it includes a lot of fuel that ignites easily when directly exposed to heat.
• Laundry Detergent – powder-based laundry detergent can be flammable due to the easy dispersal of powder into the air and volatile chemical particles in the powder.
• Hand Sanitizer – hand sanitizer is primarily made of alcohol since it kills germs very effectively, but it’s also very flammable if exposed to intense heat or a direct flame.
• Nail Polish – nail polish contains a highly reactive chemical called acetone that contains many fuel-rich particles. However, it’s only dangerous when wet; the acetone dissolves once the nail polish has dried, so it’s perfectly safe to use nail polish as long as you’re careful where you store the bottles!
• Plastic – although it’s not extremely easy to get plastics hot enough to burn, they’re made up of carbon-rich particles, so when they catch fire, they can be very dangerous. They also release carbon-rich gases as they burn, helping to sustain and spread the fire even further.
• Cotton – cotton is flammable for the same reason as paper: it’s made up of compressed and dried-out plant matter, so it contains a lot of carbon-rich fuel for fire.
• Alcohol – alcohol can be found in various household products, ranging from cleaning products to drinks. This group of chemicals releases hydrocarbon vapors that are ideal fuel for fires, so when allowed to mix with the air and exposed to heat, they can burn very intensely. In addition, the more “pure” alcohol in the product, the more explosive the product becomes – beer is far less flammable than alcohol-based disinfectants, for example.

3 Things You Wouldn’t Expect to Be Flammable

• Flour. It’s hard to believe, but that bag of flour at the back of your cupboard harbors a dark secret. When flour escapes and hangs in the air – even in small quantities – it becomes flammable. The minuscule grains burn when exposed to an ignition source and are more than capable of igniting others around them in a chain reaction that can be incredibly dangerous. For example, in 1878, 14 people were killed by a large flour dust explosion at a Minnesota flour mill.
• Oranges. Orange peel contains a highly flammable natural oil called Limonene. This substance gives the rind its distinctive bitter taste and protects the fruit from insects and mold. But, when exposed to a flame, it will ignite.
• Ping Pong Balls. Ping-pong balls are made of concentrated celluloid, which is highly flammable. So, think twice next time you’re ready to unleash that backhand; the slightest spark could see that little white ball go up in smoke!

An omnivore is an animal that eats both plant and meat-based food.

The Basics

Omnivores are some of the most successful animals in existence. Because they have a wide-ranging diet, they can find food in most environments.

Humans are perhaps the best example of this. One of the main reasons for human dominance in the natural world (aside from being able to use tools) is that we can eat both meat and plant-based foods. As a result, animals that rely on meat (carnivores) or just plants (herbivores) usually face an increased risk of starvation.

Omnivores are spread across nearly every continent and a range of different species. Most omnivores are mammals – animals that (typically) produce live offspring, are warm-blooded, and raise their babies by producing milk. However, there are certain reptiles, birds, and fish that we also class as omnivorous.

How do we tell the difference between animals?

Herbivores

Compared to carnivores and omnivores, herbivores have much flatter and less sharp teeth, including broad, spade-shaped incisors and short, blunted canines. Some herbivores have no canine teeth at all.

Big molar teeth are used to grind down plant materials for easier digestion. Herbivores use enzymes created while chewing their food to digest tough plant matter. Enzymes are chemicals used by animals and humans in their bodily processes.

Cows have a strong sense of smell. They can smell things up to 6 miles away!

Carnivores

Carnivores are famous for having enlarged and incredibly sharp canines. These are designed to tear apart meat. In addition, carnivore molars and incisors are far more jagged and pointed than those found in herbivores.

In addition, their molars have jagged edges, and their incisors have short pointed ridges that help to grasp and shred flesh. Finally, the nails of carnivores are often long and sharp. We call these claws.

Lions have some of the most prominent canine teeth of any predator.

Omnivores

Omnivores have teeth similar to both herbivores and carnivores. They have grinding molars for chewing and sharp canines and incisors for eating meat.

Omnivores share more similarities with carnivores in their teeth; however, unlike carnivores, they chew their food before swallowing it.

Humans use their teeth to chew and tear food, breaking it down before swallowing.

Ordering decimals is a process of arranging them in a specific order.

Read on to find out how to order decimals and an example of ordering decimals.

Steps of ordering decimals

1. Use a table to line up the decimal points and compare the decimals.
2. Fill in all of the numbers that you want to compare.
3. If empty squares are at the end of the decimal, fill them in with zeroes.
4. Start comparing the size of the decimal.
5. Start on the left and keep moving across to the right.

Different types of ordering

There are different ways to order decimals, just like other types of ordering for all numbers.

If you are ordering decimals in ascending order, the smallest goes first, and the numbers get bigger.

If you are descending in descending order, the most significant decimal goes first, and the numbers get smaller until you reach the smallest.

Ordering decimals: example

Now we know a bit more about ordering, let’s look at an example of ordering decimals.

Put these decimals in ascending order: 1.73, 1.073, 0.86, 0.806.

We know that ascending order means the smallest number goes first, so bear that in mind as we go through.

1. Let’s start by arranging them on a table and filling empty squares with zeroes.

1	.	7	3	0
1	.	0	7	3
0	.	8	6	0
0	.	8	0	6

2. 
   Compare the first (left) column.

In this case, you can see that two numbers start with 1, which we can ignore for now because we are looking for the smallest number.

Two numbers start with 0, so let’s move across and look at the tenth column.

3. Compare the tenth column.

We can ignore the 7 in the tenth column because it belongs to 1.73.

There are two 8s in the tenth column, which means we must move across again and see which decimal is the smallest.

4. Compare the hundredths column.

In the hundredths column, we can ignore 3 and 7 because they belong to 1.73 and 1.073.

There is a 6, which is more significant than 0. So we know that 0.86 isn’t the smallest number. So this means that 0.806 is the smallest number.

Now that we know the smallest number, we can work our way back up to the biggest.

5. Start listing the numbers from smallest to biggest.

We know that 0.806 is the smallest number and that 0.86 is the following most significant number.

So now we must look at 1.73 and 1.073 to see which comes next in the sequence. We can see that 1.73 is the biggest because it has the most significant number in the tenth column.

It allows us to slot the remaining numbers in place.

Our answer is 0.806, 0.86, 1.073, and 1.73.

Exoskeleton Animals

An exoskeleton is a hard layer outside some creatures’ bodies. An exoskeleton is an ‘external skeleton,’ the opposite of an endoskeleton.

But invertebrate insects aren’t the only creatures with exoskeletons. Spiders, centipedes, crabs, snails, and lobsters all have a kind of external armor.

Some creatures can outgrow their exoskeletons – a rigid exoskeleton can prevent development, so some animals will shed their armor and grow it again. This process is called ecdysis, or ‘molting.’ After that, there’s a period when the new exoskeleton is soft and has to harden over time.

Creatures that outgrow their exoskeletons include:

• Hermit crabs
• Spiders
• Mayflies

Except for hermit crabs, creatures with shells do not generally outgrow and shed their exoskeletons. Instead, their bodies expand as they do.

Animals with expanding shells include:

• Clams
• Molluscs
• Snails

Changing state of matter is turning solid into gas or liquid, and vice versa. Everything we see, touch, or trim is made of matter. States of matter can not be destroyed but can be turned into another with the addition or removal of heat.

Examples of Changing States

Examples of matter changes are melting (changing from solid to liquid), freezing (changing to a solid from a liquid), evaporation (changing from liquid to gas), and condensation (changing from gas to a liquid).

Changing the State of Water’s Matter

The state of water at room temperature is liquid. However, we can change the state of its matter by changing the temperature. For example, cooling water to0ºC turns the water into ice, which is solid. Hence, it is called the freezing point.

Water can also be turned into vapor, or gas, by heating it to 100ºC. It is called the boiling point. Both boiling and freezing points come at different temperatures for different substances.

Examples of Gas to Solid

The changing of gas to solid is called deposition. Here are some examples of deposition.

• Water vapor to ice – fog transforms directly into ice without becoming a liquid. It sometimes happens on windows during winter.
• Physical vapor to film – thin layers of ‘film’ placed onto a surface using the vaporized film form.

Examples of Gas to Liquid

The changing state of gas to liquid is called condensation. Here are some examples of condensation.

• Water vapor to dew – steam turns from gas to liquid, like morning dew on the grass.
• Water Vapor to liquid water – vapor makes glasses foggy after moving into a warm room from the cold.

Examples of Liquid to Gas

The changing of a liquid to gas is called vaporization. Here are some examples of vaporization.

• Water to steam is vaporized after being boiled on a stove or kettle, forming thick vapor.
• Water evaporation – water evaporates from a pool or rain puddle during hot days.

Examples of Liquid to Solid Phase Transitioning

The changing of a liquid into a solid phase transition is called freezing. Here are some examples of changing the state of matter into a frozen material.

• Water to ice – when water becomes cold enough, it freezes and turns to ice. Almost every known liquid turns to ice when cold enough – except helium.
• Liquid to crystals – lots of liquids freeze during the process of crystallization. Liquid forms into what is called a ‘crystalline solid.’

Examples of Solid to Liquid

The changing of a solid into a liquid is called melting. Here are some examples of melting matter from a solid to a liquid.

• Rocks to lava – stones in volcanos can be heated until they become molten lava.
• Metal to molten liquid – metals can be molten down and reformed into solid.
• Ice to water – ice returns to its water form after being left in temperatures above freezing.

Examples of Solid to Gas

The changing of a solid to a gas is called sublimation. Here are some examples of sublimation.

• Dry ice sublimation – carbon dioxide is called ‘dry ice’ and sublimates at room temperature.
• Freeze-drying – water can be sublimated in food produced by using a vacuum to remove air particles.

Integer numbers are whole numbers that can be positive or negative but do not have fractions or decimals.

You can use the term “integer” to describe a whole number. It means a number without a fraction or a decimal.

Unlike whole numbers, integer numbers refer to negative numbers and positive amounts.

Is 0 an integer number?

However, different people define integers in different ways. For example, some people would argue that negative numbers are integer numbers, whereas others would claim that even 0 is not an integer.

Usually, though, 0 is an integer, as are 109, 7, -3, 8, and -28. But, again, these are whole numbers with no fractions or decimals.

Examples of numbers that aren’t integers are 0.7, 1/3, -10.56, pi, and root 3. Again, it is because they are not whole numbers.

So there are three types of integers:

• Positive numbers
• Negative numbers
• Zero

What are integers used for in everyday life?

Common sense sometimes tells you you need an integer to find the answer to a question. For example, if you’re painting a wall and need 2.3 tins to cover it, you’ll have to buy three tins. You can’t buy 0.3 tins of paint to get the exact amount you need. Sometimes, you have to round up to an integer.

However, you’ll see integers used everywhere in daily life. Everything from the calendar to the binary code uses integers to represent information.

That’s why getting a good understanding of them at a young age is so essential.

Role Models

Young people are impressionable and need role models around them to set a good example. Unfortunately, more often than not, their role models are sportsmen and superheroes.

But teachers can be excellent role models for children too. Especially in primary school, children need people who they can emulate in their values, attitudes, and actions.

Teachers can be role models for their students in many ways. People admire their role models and aspire to be like them, which is why teachers can be excellent role models for children. People may also look to their role models for advice and guidance, especially for children needing extra support. For some children, teachers may become some of the most influential people in their lives. Teachers also help their students through an essential stage of development.

Think about the positive ways that you can present yourself as a role model. You’re not just hired to pass on information and knowledge: the best teachers are people students aspire to be like.

Here are some tips on how a teacher can be an excellent role model:

• Motivate your students and promote positivity
• Be approachable
• Lead by example
• Be a mentor for children by listening, supporting, and giving reliable, neutral, and objective advice.
• Encourage your students to be ambitious and have dreams or aspirations
• Encourage the idea of fairness, equality, and equal opportunities for all in the classroom

Guidance

Teachers aren’t just there to help children improve academically. They also help children to grow in their personal lives.

Being a teacher is like having five jobs in one: you’re a teacher, mentor, therapist, and friend. When you spend hours a day with the same kids, you’re bound to get to know what they do outside of school too.

Teaching your students about science and maths is all good, but you also have an excellent purpose of guiding them through life. So it’s essential to remember that you can help them to thrive as people, not pupils.

Inspiration

We all had an uninteresting teacher who just read out of a textbook. But conversely, the best teachers go above and beyond to inspire children through learning.

Primary school is where many kids get an idea of how they want to spend their lives. Learning about the human body won’t just help them pass their SATs exams: it could also convince them to become doctors or scientists.

Teachers are essential in inspiring young people and showing them the value of their learning.

Shape The Future

Teachers have a unique position as they hold the future. They can mold and shape the values and attitudes of the next generation to create a fairer and more equal society.

By being a role model and inspiring your students, you’re setting up a vision for what you want the future to look like. Plant the seeds now, and a better world can grow.

New Ways Of Seeing

Many factors determine how children see the world: their family, cultural background, and class status. As teachers, it’s your role to open up their minds and help them to look beyond what they already know.

Being a teacher isn’t about upholding the status quo. Instead, it’s about showing children new ways of seeing, be it looking at a debate from a new perspective or offering them a culture they aren’t familiar with.

Bring Learning To Life

If all teachers did was pass on information, technology would make their jobs obsolete. But there’s a reason why robots aren’t taking over the profession.

Teachers are instrumental in bringing learning to life. In addition, teachers are essential in grounding learning in the real world by providing relatable examples and finding creative ways to teach the curriculum.

The Future Of Work

Getting a job is not the only reason children spend 18 years in education. Learning shouldn’t just be about completing an end goal, like good exam results or a shiny new job. It’s about how you guide students through the world.

Likewise, securing jobs for all your students is not your job. But you do play an essential role in preparing them for work. As they move from their early years to primary and secondary school, teachers play a huge role in preparing students for the ‘real’ world outside of the school bubble.

From exploring job opportunities to opening their eyes to the careers they can excel at, teachers are integral in building up their students to succeed.

In science, matter can exist in three states: solid, liquid, and gas. These three states have distinct properties that allow humans to identify them.

To support teaching your children about states of matter, look at this collection of helpful teaching resources.

Changing States of Matter

Changing state of matter is turning solid into gas or liquid, and vice versa. Everything we see is made of matter, and this matter can change state with the addition or removal of heat.

In KS2, children will learn about the different states of matter. This topic mainly explains how a material’s state of matter can change.

What are the 6 Changes of Matter?

Matter changes state in various ways:

• Melting – changing from solid to liquid
• Freezing – changing from a liquid to a solid
• Vaporization – changing from liquid to gas
• Condensation – changing from gas to a liquid
• Deposition – changing from gas to a solid
• Sublimation – changing from a solid to gas

These changing states of matter occur due to a temperature change. For example, ice (a solid) will melt when the temperature increases and return to the water (a liquid).

Why are There Different States of Matter?

All matter is made up of tiny particles, regardless of what state the matter is in. Every particle within these materials has a certain amount of kinetic energy that allows the particles to move. In a solid material, these particles are tightly bonded together, with minimal movement, to form a single unit that doesn’t change shape or size. However, heating the solid up gives the particles more energy that they can use to move, weakening the bonds between the particles and gradually allowing the solid to turn into a liquid.

In a liquid, the particles are still loosely bonded, but rather than being a rigid bond that holds all the particles within a fixed pattern like a solid, the bonds are much more flexible, allowing the liquid to change shape depending on what container it sits within. The bonds are still close enough that the liquid will retain the same volume, though – it can’t get any bigger or smaller, only change shape. Heating the liquid further still gives the particles enough energy to break the bonds between them almost entirely, allowing the liquid to become a gas.

In a gas, there are no bonds between the particles, so they can move freely, allowing the gas to change shape and volume depending on the available space. In many cases, their particles are so diffused that they’re invisible to the naked eye.

All these processes can be carried out in reverse, converting a gas into a liquid or a liquid into a solid. Throughout all of these changes, the particles in a substance are the same whether it’s in the solid, liquid, or gas state – the only thing that changes is the arrangement and movement of the particles.

Each of these states of matter can also be referred to as a Phase, with changes of state being referred to as phase changes.

What’s an excellent example of how this works in everyday life?

Water is one of the best materials you can use as an example of how changing states of matter work in everyday life. Below 0°C, water freezes and becomes a solid material, ice. Once the ice is brought back over 0°C, it melts, becomes liquid water, and can be heated up to 100°C. At 100°C, water boils and becomes a gas, water vapor.

Although water is effortless to observe, since it’s not too challenging to bring water both to the “boiling point,” where a liquid becomes a gas, and to the “freezing point,” where the liquid becomes a solid, most other materials also behave similarly. Almost every material has a freezing and boiling point the same way water does, but many of them, like most metals, have such a high freezing (or melting) point that it’s tough to get them hot enough to become a liquid. Metals are an excellent example of this – while industrial forges can get metal to melt, it’s not something that can be done without an incredibly intense heat that’s hard to find in the natural world.

Now that we’ve explored why matter exists in different states and how matter can change between them let’s focus on each state and how we can identify them in the world around us.

What are the Properties of Solid Materials?

The properties of solids include:

• Solids stay in one place and can be held.
• Solids keep their shape. They do not flow like liquids.
• Solids always take up the same amount of space. They do not spread out like gases.
• Solids can be cut or shaped.
• Even though they can be poured, sugar, salt, and flour are all solids. So each salt particle, for example, keeps the same shape and volume.

It is because of the way that the particles in a solid are bonded together. They’re very closely packed into a regular pattern, with rigid bonds that hold the particles into a tightly packed structure.

Since the particles can’t move, solid materials have a fixed shape and cannot flow (although materials like sand seem to flow, the individual sand grains can’t change shape or size like water can). It is also hard to compress something made of solid material: the particles are tightly packed together, so there’s no room for them to move into a different position and allow the solid to change shape. Solids will change state of matter when heat is present as the particles start to move.

Some examples of solids that we might find in the world around us are: ice, wood, sand, and metal

It is because of the way that the particles are bonded in a liquid. The particles in a liquid are closely related, but these bonds are looser and more flexible than in a solid, allowing the particles to slide and form random shapes within the mass of liquid. In contrast, solids have a regular, ordered structure of particles.

It is why liquids, unlike solids, can flow and change shape: although the particles are closely bonded together, they can move around within these bonds, allowing the liquid to shift to fill different shapes. The bonds are strong enough that the liquid can’t expand or shrink, however – while the shape of the liquid can change, and it might seem bigger or smaller depending on the container it’s currently held in, the volume of liquid will always stay the same.

These close bonds are also why liquids are extremely hard to compress: the particles are closely packed in, the same as solids, so if a liquid is in a container with a fixed shape so that it can’t further change shape, there isn’t enough space between the particles for them to be compressed further.

Some examples of liquids that we might find in everyday life are: water, milk, cooking oil, and honey

These properties are all caused by how the particles bond in a gas. Unlike in liquids and solids, the particles in a gas have fragile bonds to the extent that they’re barely bonded. It allows the particles to move freely in all directions, not held together in a homogenous mass like liquids and solids. As a result, gases flow like liquids and can expand or shrink to fill the space they currently occupy since the particles move around so freely that the mass becomes highly fluid.

It is also why gases can be compressed, unlike liquids and solids. Since the particles in gases naturally travel freely, when they aren’t compressed, they’ll expand to fill whatever space is available, with lots of space between the individual particles. It means that when placed under pressure, the particles have plenty of space left between them that can be removed as the space the gas fills is compressed.

Some examples of gases we might find worldwide are water vapor (steam), helium, nitrogen, and oxygen.

Changing States of Matter: Examples

Examples of Gas to Solid

The changing of gas to solid is called deposition. Here are some examples of deposition.

• Water vapor to ice – fog transforms directly into ice without becoming a liquid. It sometimes happens on windows during winter.
• Physical vapor to film – thin layers of ‘film’ placed onto a surface using the vaporized film form.

Examples of Gas to Liquid

The changing state of gas to liquid is called condensation. Here are some examples of condensation.

• Water vapor to dew – steam turns from gas to liquid, like morning dew on the grass.
• Water vapor to liquid water – fog makes glasses foggy after moving into a warm room from the cold.

Examples of Liquid to Gas

The changing of a liquid to gas is called vaporization. Here are some examples of vaporization.

• Water to steam is vaporized after being boiled on a stove or kettle, forming thick vapor.
• Water evaporation – water evaporates from a pool or rain puddle during hot days.

Examples of Liquid to Solid

The changing of a liquid into a solid phase transition is called freezing. Here are some examples of changing the state of matter into a frozen material.

• Water to ice – when water becomes cold enough, it freezes and turns to ice. Almost every known liquid turns to ice when cold enough – except helium.
• Liquid to crystals – lots of liquids freeze during the process of crystallization. Liquid forms into what is called a ‘crystalline solid.’

Examples of Solid to Liquid

The changing of a solid into a liquid is called melting. Here are some examples of melting matter from a solid to a liquid.

• Rocks to lava – stones in volcanos can be heated until they become molten lava.
• Metal to molten liquid – metals can be molten down and reformed into solid.
• Ice to water – ice returns to its water form after being left in temperatures above freezing.

Examples of Solid to Gas

The changing of a solid to a gas is called sublimation. Here are some examples of sublimation.

• Dry ice sublimation – carbon dioxide is called ‘dry ice’ and sublimates at room temperature.
• Freeze-drying – water can be sublimated in food produced by using a vacuum to remove air particles.

Are There Other States of Matter?

There is a fourth state of matter: plasma. Plasma is very similar to gas, but it’s made up of particles that are charged with energy that causes the particles to split and form a different configuration. Unlike the other three states of matter, it’s unclear what causes matter to transition into plasma, although we know it depends on positively charged particles. However, although we don’t fully understand plasma, it can be observed in the world around us.

Two examples where plasma is on show in everyday life are in neon lights and lightning, but in space, plasma’s most common because all the stars, including our sun, contain vast quantities of plasma. As a result, plasma is the most abundant form of ordinary matter in the universe, excluding dark matter and dark energy.

However, if you’re looking for a straightforward explanation for younger children, don’t panic! Most academic curriculums don’t cover plasma until university, so you don’t must worry about covering it with more youthful pupils.

What Determines a Material’s State of Matter?

While the primary determiner of a material’s state of matter is temperature, as we’ve already discussed, another significant factor we haven’t mentioned is pressure. Because humans can’t survive outside of a relatively narrow band of atmospheric pressures (between 0.0621 standard atmospheres and 30 standard atmospheres) without using specialized gear, it can be a little difficult to observe the role pressure can play in determining a material’s state of matter. Still, there are environments and conditions where it can be seen.

Generally speaking, when the pressure exerted on a substance increases, it can cause the substance to condense. Decreasing pressure can cause it to vaporize. For some types of rock, decreasing pressure can also cause them to melt.

It is most easily visible when we look at the water around hydrothermal vents at the bottom of the sea. Although the temperatures around these vents are incredibly high, reaching around 400°C, four times the boiling point of water, the pressure is so high that the water cannot vaporize and stays as a super-heated liquid!