Lesson video

Hello again.

My name is Miss Couves.

How are you today? This is our last lesson on states of matter.

I am particularly excited about our lesson today because we are going to end today's lesson with an investigation.

I am so excited, I am already wearing my lab coat, ready to go.

I really like doing investigations because I get to see all of the science in action.

And we can use all of our scientific knowledge to explain what is happening.

Are you ready? Let's get started.

In today's lesson we will start by recapping our previous knowledge.

We will then look at some examples of substances that are hard to categorise as a solid, a liquid, or a gas.

Then we will learn about non-Newtonian fluids and their properties.

And we'll finish by investigate them.

In this lesson you will need an exercise book and a piece of paper and a pencil.

If you don't have one of these things, pause the video now and go and get them.

If you would like to take part in our experiment, you will also need some corn flour, some water, and a place to do a very messy experiment.

You'll also need to ask an adult to help you with your experiment.

Let's start by recapping our previous knowledge.

What do the particles look like in solids, liquids, and gases? Point to the diagram of a liquid.

The liquid is the diagram on the left-hand side.

How did you know? This diagram shows a liquid because the particles are touching, but they are arranged randomly.

Point to the diagram of a solid.

The diagram of the solid is on the right-hand side.

How do you know that this diagram represents a solid? This diagram represents a solid because the particles are touching and arranged in ordered rows.

Point to the diagram of the gas.

The gas is the diagram in the middle.

How did you know? This diagram is a gas because the particles are far apart and moving very fast.

Can you remember the properties of solids? Pause the video and write down three properties of solids.

Solids cannot be compressed, they do not flow, and they have a fixed shape.

Can you remember the properties of liquids? Pause the video and write down three properties of liquids.

Press play when you're ready to continue.

Liquids cannot be compressed, they can flow, and they can take the shape of the bottom of their container.

Can you remember the properties of gases? Pause the video and write down three properties of gases.

Gases can be compressed, they can flow, and they can fill the shape of their container.

Pause the video and write three sentences to match the description to the correct states of matter.

Press play when you're ready to find out the answer.

Solid particles are touching and in ordered rows.

Liquid particles are touching in a random arrangement.

Gas particles are far apart from each other.

Write three sentences to match the description to the correct state of matter.

Pause the video and press play when you are ready to hear the answers.

Solid particles cannot move but can vibrate.

Liquid particles can slide past each other.

And gas particles are moving constantly in all directions.

Which state of matter.

Which state change does each arrow represent? Pause the video and complete the diagram in your notes.

Press play when you're ready to hear the answers.

When a solid becomes a liquid it's called melting.

When a liquid becomes a gas it's called boiling.

When a gas becomes a liquid it's called condensing.

And when a liquid becomes a solid it's called freezing.

Temperature is measured using a scale called? Celsius, well done.

Zero degrees is the temperature at which water melts.

Hundred degrees is the temperature at which water boils.

A fixed point is a temperature at which a state change happens for a particular substance.

What are the two fixed points scientists use most often? Melting point and boiling point.

What is a melting point? The melting point is the temperature at which a substance melts.

What is the boiling point? The boiling point is the temperature at which the substance boils.

How do we know if something is a solid, a liquid, or a gas? We know something is a solid if it has not melted or boiled.

We know something is a liquid if it's melted but not boiled.

And we know something is a gas if it has melted and boiled.

Goodness me, what's a lot of knowledge we already had inside our brains.

We're now going to add a small bit extra about solids, liquids, and gases and substances that don't quite fit into these categories.

We are going to look at two substances that are difficult to categorise as a solid, a liquid, or a gas.

First, let's look at sand.

Sand behaves like a solid because the grains have a fixed shape.

I have some sand here, let's have a look at it.

Can you see that the grains of sand all have a fixed shape? Let's try compressing our sand.

I can move the sand around but I can't make the grains of sand compress.

So the sand particles have a fixed shape and they cannot be compressed.

Sand looks like it probably is solid.

Let's have a look at what happens when we pour sand from one container to another.

It's a solid, so what are we expecting? We're expecting it to keep it's shape.

Wow, did you see that? Let's have a look again.

Sand is able to flow and take the shape of the bottom of its container.

It's that a property of a solid? No, that's a property of a liquid.

So sand behaves like a solid and like a liquid.

Let's think about that again.

Pause the video and write down two sentences, one about how sand behaves like a solid, and another about how sand behaves like a liquid.

Press play when you're ready to find out about the next substance.

Now we're going to think about jelly.

Is jelly a solid, a liquid, or a gas? Jelly has a fixed shape, if you put it in a different container, it will still have the same shape.

However, jelly wobbles, which means that the particles can move over each other.

Which of these is a property of a solid? Jelly is a solid because it has a fixed shape.

Which is the property of a liquid? The particles being able to move over each other is a property of a liquid.

Pause the video and write down two sentences, why is jelly like a solid and why is jelly like a liquid.

Press play when you're ready to find out about non-Newtonian fluids.

Next, we're going to learn about another substance that is hard to categorise, called a non-Newtonian fluid.

My turn, non-Newtonian fluid.

You're turn.

We're going to practise that one again because it is a really hard word to say.

Non-Newtonian fluid.

Your turn.

Non-Newtonian fluid, well done.

I'm going to show you a non-Newtonian fluid.

I have made a non-Newtonian fluid in my bowl, here.

I have made my non-Newtonian fluid by mixing water and corn flour.

I'm going to show you some of the properties of my non-Newtonian fluid.

Non-Newtonian fluids act like a liquid and like a solid.

Can you see how it's acting like a solid when I hit it hard and acting like a liquid when I pour it gently? That is so interesting.

What if we try and take the spoon out slowly? If I take the spoon out slowly, it flows like a liquid.

If I try and take the spoon out fast.

Ugh, I can't do it! It behaves like a solid.

Let's try putting the spoon in slowly.

If you put the spoon in slowly, I can stir it like a liquid.

Let's try putting the spoon in fast.

Ah! When I try to put this using force, it behaves like a solid.

And when I don't use much force it behaves like a liquid.

When does a non-Newtonian fluid behave like a solid? Non-Newtonian fluid behaves like a solid when I apply a force.

When does a non-Newtonian fluid behave like a liquid? A non-Newtonian fluid behaves like a liquid when there isn't much force.

In our experiment later, you're going to have a go at looking at those properties of non-Newtonian fluids.

Non-Newtonian fluids changed their behaviour when a force is applied.

When a force is applied, they behave as a solid.

When a force is not applied, they behave as a liquid.

When do non-Newtonian fluids behave like a solid? Non-Newtonian fluids behave like a solid when a force is applied.

When do they behave as a liquid? They behave as a liquid when no force is applied.

Pause the video and write down what makes a non-Newtonian fluid change its behaviour.

A non-Newtonian fluid changes behaviour when a force is applied.

We are going to investigate the properties of non-Newtonian fluids together.

If you would like to do this experiment yourself, you will need to find an adult and ask them to help you.

You will need corn flour and water and a place to do the experiment.

This is a very messy investigation.

So make sure you ask a parent or carer if you can use corn flower and water to make a non-Newtonian fluid.

Cover your clothes in case they get messy.

Do the experiment somewhere where it's okay to get messy and cover the area you're working in and anything that you don't want to get messy.

Pause the video now and go and get an adult to help you.

If you don't want to do the experiment or you don't have corn flour and water, you can watch me do the experiment and you'll learn just as much.

This is how we're going to make our non-Newtonian fluid.

I am wearing my lab coat to keep my clothes clean and I've covered the table with scrap paper, in case I make a mess.

I'm going to be as careful as possible as I make my non-Newtonian fluid.

When I make my non-Newtonian fluid, I need to add corn flour and water together.

I need to add twice as much corn flour as water to my bowl.

Okay, let's make our non-Newtonian fluid.

Into my bowl I'm going to put twice as much corn flour as water.

I'm going to use the same size cup to make sure I use the same amount of corn flour.

I'm going to use one full cup of corn flour and half a cup water.

Okay.

There is my cup of corn flour.

And to my cup of corn flour, I'm going to add half a cup of water.

Now I've added these things together, I need to slowly mix up my corn flour and water.

Remember that if you stir too much and apply too much force, it will behave like a solid.

I've added too much water and my corn flour and water mixture is just behaving as a liquid.

So I'm going to add some more corn flour.

If your non-Newtonian fluid is behaving like a liquid, you need to add more corn flour.

If it's behaving only like a solid, you need to add more water.

Can you see now that as I try to stir, it's starting to behave like a solid.

When you have the consistency right it will behave like a solid when you apply a force and a liquid when you don't.

Oh, there we go.

Remember that you need to stir slowly otherwise you apply too much force and it will start behaving like a solid.

I think my non-Newtonian fluid is ready for our investigation.

Okay.

Let's have a look at what we're going to do in our investigation.

The first thing we're going to do is try grabbing our non-Newtonian fluid quickly.

I'm going to take my spoon out and I'm going to try and grab it quickly.

Oh, when I tried to grab it quickly, it behaves like a solid.

Can you see that? Is yours doing the same? Now we're going to try releasing our hand slowly.

Can you see it when you release your hands, it turns back into a liquid.

So it was a solid and then it becomes a liquid.

I'm going to use this one because there's too much in this bowl.

It's a solid when I apply a force and a liquid when I release it.

A solid when I try to grab it and then a liquid when I release it.

Now we're going to try dragging our hands quickly then slowly.

Quickly it's really hard.

And then slowly I can pull it through.

You can carry on having a go at those three activities.

I'm going to show you this full screen so that if you're not doing the experiment, you can still see.

So I'm going to start by trying to grab my non-Newtonian fluid quickly.

Oh, when I do it quickly, can you see that it's behaving like a solid? Now I'm going to let it go.

Can you see that it's turning into a liquid? The next thing I'm going to do is try moving my hands through it really fast.

Oh, when I move through it really fast, it turns into a solid.

And when they move my fingers through it slowly, it behaves like a liquid.

What changes the properties of a non-Newtonian fluid? Properties of a non-Newtonian fluid changes when we apply a force.

When we apply force it behaves like a solid.

And when we don't apply force it behaves like a liquid.

Let's look at our last three activities to try.

We're going to try tipping the bowl to the side quickly.

Remember, don't tip it all the way upside down, otherwise you're going to make a mess.

Try tipping it to the side quickly.

Oh, can you see that it becomes a solid and it doesn't move? Now we're going to try tilting it slowly.

Can you see that it flows like a liquid when you tilt it slowly? And it stops like a solid if you do it quickly.

Now we're going to try and pick it up and squash it into a ball.

There you go, if you roll it around, you can make it ball.

You can keep playing with those properties of non-Newtonian fluids.

I'm going to show you this full screen, so if you're not doing the experiment, you can see.

When I flip my bowl to the side quickly, it acts as a solid and it doesn't move.

When I move it slowly can you see that it flows like a liquid? I can pick up my non-Newtonian fluid and make it into a ball.

Can you see that if I keep rolling it, it stays as a ball, but as soon as I stop, it turns back into a liquid? My hands are so messy.

Pause your video now and go and clean your hands so that you're ready to write up your notes from our investigation.

Goodness me, that was a messy experiment.

I hope you have cleaned your area, so you're ready to write up your results.

I would like you to pause the video and write three sentences to say what happened when you tried these three experiments.

Pause the video and answer the three questions.

Press play when you're ready to see the next three.

Now we're going to write down what happened when we did these three experiments.

Pause the video and write down what happened when you tried to do each of these things.

We found out that non-Newtonian fluids behave differently when a force is applied.

When a force is applied, they behave like a solid.

And when it's not, they behave like a liquid.

We had so much fun today learning about non-Newtonian fluids and making a little bit of a mess.

I hope you enjoyed making your own non-Newtonian fluid and investigating its properties.

You have learnt so much in this unit.

Your heads are now full with scientific facts.

Make sure you complete the quiz to show off all of your knowledge.

Bye.