Lesson video

Hello, my name is Mrs. Mherin, and I'm really excited to be learning all about thermal insulators with you today.

And we are going to be doing some planning.

Welcome to today's lesson from the unit Properties Changes and Separating Materials.

Now, your learning outcome today is "I can plan to investigate the physical property of thermal insulation." Now, I know that learning can sometimes be a little bit challenging, but that's okay because it just means that we are going to work really hard together and we're going to learn lots of fabulous new things.

Now, before we begin, here are your keywords for today's lesson.

I am going to be referring to these keywords throughout today's lesson.

However, if you find it helpful to have these written down, you can pause video here and have a go at doing that.

Off you go.

Fantastic, well done.

Now, your lesson today is split into two parts.

Let's begin with the first part, keeping things hot or cold.

Now, Laura and Jun both have a cup of hot chocolate, and they left their warm drinks on the table during break time before coming inside to drink them.

Laura says, "My hot chocolate is still too warm to drink." And Jun says "Mine has gone cold." Now, both drinks came from the same big jug of hot chocolate.

So why has Jun's gone cold, but Laura's is still too hot to drink? I'll give you five seconds to think about your answer.

Off you go.

Fabulous.

Well done.

So the reason why is because Jun and Laura are using different types of cups.

Laura's cup is made of plastic and Jun's cup is made of ceramic.

Now, why do you think that would affect the temperature of their drinks? Again, I'll give you five seconds to think about your answer.

Off you go.

Fabulous.

Well done.

Now, different materials have different physical properties, and one property is how well materials allow heat to pass through them.

Now, let's do a quick check-in of your learning before we continue.

So different something have different physical properties.

So is it different scientists, different materials, or different colours? I'll give you five seconds to think about your answer.

Off you go.

Well done.

The answer is material.

So different materials have different physical properties.

Fantastic.

Well done.

Now, a material that does not allow electricity to pass through it easily is called an electrical insulator.

Material that does not allow sound to pass through it easily is called a sound insulator.

Now, we use a similar term to talk about heat.

Do you know the name of this physical property? I'll give you five seconds to think about your answer.

Off you go.

Well done.

So materials which do not allow heat to pass through them easily are called thermal insulators.

Now, thermal is an adjective that means related to heat.

So have you ever worn clothes like this as underlayers, possibly in winter? Now, these are called thermals or thermal base layers.

Now, thermal clothing is designed to work as a thermal insulator and prevent you from getting cold.

And thermal insulators don't just keep warm things warm.

Remember, thermal insulator is a material that does not allow heat to pass through easily.

That means it can keep warm things warm, but it can also help to keep cold things cold.

And thermal insulators slow down the speed of temperature change.

Now, here is your first task for today.

It says the children are discussing thermal insulators.

Laura says, "Thermal insulators help to keep things warm." Jun says, "Thermal insulators help to keep things cold." And Alex says, "Thermal insulators help to keep warm things warm and cold things cold." Who do you agree with and why? So I'd like you to pause the video now, and write down who you agree with, and give me an explanation for it as well.

Okay, so pause the video here and have a go at doing this activity.

Off you go.

Well done.

So Alex is correct.

A thermal insulator is a material that does not allow heat to pass through easily.

It slows down the speed of temperature changes.

Now, we're on to the second part of our learning today, which is planning to investigate thermal insulators.

Now, Laura says, "My hot chocolate is still too warm to drink." And remember Jun's went cold.

Now, the children's hot chocolate drinks are different temperatures because one of the cup allows heat to pass through it more easily than the other.

Now, whose cup do you think is a better thermal insulator, and how do you know? So remember, think back to what you know about thermal insulator.

Whose cup is better? Whose cup is a better thermal insulator, and how do you know? Okay, I'll give you five seconds to think about your answer.

Off you go.

Fabulous.

Well done.

Laura's cup is a better thermal insulator because it allowed less heat to pass from the hot chocolate through the cup to the cooler surrounding air.

So Laura's plastic cup, some of the heat did escape.

However, because it's a good thermal insulator, there was less heat passing from the hot chocolate through the cup to the cooler surrounding air.

So it stayed hotter.

Whereas Jun's ceramic cup is not a good thermal insulator, and, therefore, more heat was able to pass out from the hot chocolate through the cup and to the cooler surrounding air.

And this is why Laura's drink has stayed warmer than Jun's.

Now, different materials can be suitable or unsuitable for thermal insulation, depending on their physical properties.

So materials used to make winter hats, gloves, and scarves are suitable thermal insulators, and that's because they are designed to keep us warm.

Now, if they weren't good thermal insulators, then they wouldn't be doing a very good job, and we would be very cold in winter, and there would be no point in wearing them.

Now, wool and fleece fibres form millions of tiny air pockets that trap the air and slow the transfer of heat.

Now, do you think glass is suitable or unsuitable for thermal insulation based on its physical properties? So what do you think? I'll give you five seconds to think about your answer.

Off you go.

So glass is actually a very poor thermal insulator, and lots of the heat that is lost from buildings is through the glass of windows.

And that's because glass allows heat to escape more easily than most other building materials.

Now, let's do a quick check-in of your learning so far, what determines whether a material is suitable or unsuitable for thermal insulation? Is it its price, its size, its properties, or its weight? I'll give you five seconds to think about your answer.

Off you go.

Well done.

The answer is its properties.

So the properties determine whether a material is suitable or unsuitable for thermal insulation.

Now, Jun is keen to learn more about thermal insulators and he says, "I want to test different bowls to compare how well they keep my soup warm.

Which type of inquiry should I choose?" What do you think? I'll give you five seconds to think about your answer for this.

Off you go.

Wonderful.

Well done.

So Laura says, "A fair test and a comparative test can be used to investigate how changing one variable in an investigation affects another variable.

Because we are comparing different objects, I think we should use a comparative test." Now, I want you to explain to a partner what a comparative test is.

Okay, so I'll give you some time now.

You can pause the video here and talk to a partner about what a comparative test is.

Off you go.

Fantastic.

Well done.

So a comparative test is a little like a fair test, and it's an investigation in which only one variable is changed when attempting to answer a scientific question.

So in a comparative test, the variable that is being changed has names or labels, such as the names of different materials.

Now, Jun has decided to change the material of the bowl and he says, "My question is: Which material is most suitable for keeping my soup warm?" Now, to answer this question, Jun will measure the temperature of the soup when it's served into bowls made out of different materials and observe how the temperature changes over time.

Now, the bowl with the smallest change in temperature will be the best thermal insulator.

Now, how many variables should you change in a comparative test? Is A, none, B, one, C, all variables, or D, it doesn't matter? I'll give you five to think about your answer.

Off you go.

Fantastic.

Well done.

The answer is one.

Now, Jun will change the material of the bowls and measure the temperature of the soup over time.

Which variables will he need to control and keep? So which things is he going to keep the same? So I'll give you five seconds to think about your answer.

Off you go.

Fabulous.

Well done.

So in a comparative test, only one variable is changed and one measured.

All other variables must be controlled.

When we control variables, it means we keep them the same throughout an investigation.

So what are the variables that Jun can control? I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

So the amount of soup is one.

The type of soup.

The start temperature of the soup.

The temperature of the room.

The time he carries out the experiment for.

Are there any variables that are more difficult to control? Again, I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

So there are some variables that Jun cannot control easily.

Now, I'll giving you some time to have a think, but can you think of any more? Again, I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

So, "When using bowls of different materials I will try to use bowls that are a similar size, thickness, and shapes, but unless I get them specially made for this investigation, the bowls will not be exactly the same." Because the material of the bowl is not the only variable that will change, the different materials will not be compared in a fair way.

So Jun considers his investigation again.

And he says, "There are some variables that I cannot control in this investigation, so I will need to change my inquiry question to 'which bowl is most suitable for keeping my soup warm' rather than 'which material is most suitable for keeping my soup warm.

' Now, Laura is going to use what Jun has learned to set up her own comparative test.

She says, "I want to test the thermal insulation of the cups in my house.

I will compare the type of cup as there are some variables such as cup size, thickness, and shape that I can't control." And here are the different cups from Laura's house.

Now, true or false? When we control variables, it means we change them throughout an investigation.

Is that true or false? I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

The answer is false.

Now, let's see if you can justify your answer.

Is that because when we control the variables, we keep them the same, or when we control variables, we need to measure them? Again, I'll give you five seconds to think about your answer.

Off you go.

Fabulous.

Well done.

The answer is A, when we control variables, we keep them the same.

Now, here is task B.

It says, plan a comparative test using different cups to answer the inquiry question, "which cup is most suitable for keeping warm water warm?" I want you to discuss the following.

So what you're going to do.

Which variable will you change? Which variable will you measure and how? And which variable will you control? So I'd like you to pause video here and have a go at task number one.

Off you go.

Wonderful.

Well done.

So to keep safe, you can only use water up to 50 degrees because I don't want you to burn yourself.

Now, the second one is to record your ideas with a label diagram and a list of numbered instructions for your method.

So again, I'd like you to pause the video here and have a go at doing this activity.

Off you go.

Fabulous.

Well done.

So the variable we will change is the type of cup, and the variable we will measure is the temperature change over time.

Now, the variables we are going to control are the amount of warm water that has to be the same, the starting temperature of the water, remember no more than 50 degrees, the temperature of the room, and how long we carry out the experiment.

Now, here are some numbered instructions for the method.

Number one, pour 100 mils of water into three different types of cup.

As soon as the water is in each cup.

Measure the temperature of the water using a thermometer.

Record this as the temperature at zero minutes.

Time 10 minutes using a timer.

Then, measure and record the temperature of water in each cup again.

And then, calculate the difference in temperature for the water in each cup.

So your diagram may have looked a little like this.

So we've got the thermometers, the timer, the different cups, and 100 millilitres of warm water.

Now, we are on to the summary of our learning today.

Different materials have different physical properties.

A thermal insulator is a material that does not allow heat to pass through easily.

Different materials can be suitable or unsuitable for thermal insulation, depending on their properties.

In a comparative test, the variables that is being changed has names or labels such as the names of plants.

When we control variables, it means we keep them the same throughout a comparative test investigation.

Now, I am really, really proud of your fantastic effort in today's lesson.

Well done on creating such wonderful plans.