Hello, my name is Mrs. Mehrin, and I'm so excited to be learning all about melting temperatures with you.

And today, we are going to be doing some planning.

Let's begin.

Welcome to today's lesson from the unit Introduction to States of Matter and Changing States.

Your learning outcome is, I can plan how to find the temperatures at which some common materials melt.

Now, we are going to be referring back to some of your previous learning where we did some research, and today we are going to be doing some planning.

Now I know that learning can sometimes be a little bit tricky and a little bit challenging, but that's okay because it just means that we are going to learn some wonderful things together and we are going to work really hard.

So let's begin.

So here are your four keywords for today.

If you find it helpful, you can pause the video here and jot them down.

However, I am going to be referring to them throughout today's lesson.

If you'd like to jot them down, you can pause the video now.

Off you go.

Fantastic.

Well done.

So your lesson today is split into two parts.

Let's begin with the first part, Melting Temperature.

So Laura and Andeep are sharing a packet of chocolate buttons.

Laura is holding hers in her hand and she says, "The chocolate buttons have gone soft in my hand." Why do you think this has happened to Laura? I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

So Laura's hand is warm and is heating the chocolate buttons.

The solid chocolate has begun to change into chocolate in the liquid state, and we can see the chocolate in the liquid state here in this picture.

Now Laura says, "I can't remember what this process is called." Can you? Can you remember what the process is called when you make something that's in a solid state into a liquid state? I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

The process in which a solid changes to a liquid is called melting.

And Andeep says, "The chocolate buttons are melting on Laura's hand." Now, Andeep's chocolate buttons are on a plate and they have not begun to melt.

The chocolate in Laura's hand has reached its melting temperature, but the chocolate on Andeep's plate has not.

And the reason why Laura's has reached its melting temperature is because of Laura's body heat.

Now different materials melt at different temperatures.

Andeep says, "Snowmen are made from water in the solid state, snow and ice.

They melt in the sun." And Laura says, "Solid butter melts in a pan on a hob." And Sofia says, "Even solid metal melts when it's heated to very high temperatures." Now the melting temperature of a material is the temperature at which it changes from solid to liquid.

Water in the solid state is known as ice.

Do you know the temperature at which ice melts? Can you remember from our last lesson? I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

It melts at 0 degrees Celsius, so the melting temperature of water in the solid state is 0 degrees Celsius, or 0 and then this symbol here where you've got small circle and then a C, which means Celsius.

So let's do a quick checking of your learning.

It says, what is the name of the process in which material changes from the solid state to the liquid state? Is it called A, liquefying, B, melting, C, burning, or D, decomposing? I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

The answer is B, melting.

Now the melting temperature is the temperature at which a A, a liquid changes to a solid, solid changes to a liquid, or C, liquid changes to a gas.

Again, I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

The answer is B, solid changes to a liquid.

Now here is your first task and it says, Andeep and Laura try to melt chocolate buttons by placing them over water.

And I want you to explain why Laura's chocolate melts but Andeep's chocolate doesn't melt.

Use the phrase, "melting temperature," in your explanation.

So I'm going to give you some time now.

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

Off you go.

Fantastic.

Well done.

So remember I wanted you to explain why Laura's chocolate melts but Andeep's chocolate doesn't melt.

And I wanted you to use the phrase, "melting temperature," in your explanation.

So your explanation may have been like this.

"Laura's chocolate buttons melted because they were heated by the warm water and reached the melting temperature of chocolate." "Andeep's chocolate buttons didn't melt because the cold water did not heat the chocolate enough to reach the melting temperature of chocolate, so the chocolate stayed in the solid state." So now we are on to the second part of your learning today, which is Investigating Melting Temperatures.

Different materials melt at different temperatures.

Andeep says, "I know that aluminium, a metal, and water melt at different temperatures because at room temperature, aluminium is in the solid state but water is in the liquid state." Now, materials that are liquid or that are in the liquid state at room temperature have melted.

They have a melting temperature lower than the room temperature.

So here is the thermometer showing the room temperature of 19 degrees Celsius.

Now materials that are in the solid state at room temperature have not melted.

They have a melting temperature higher than the room temperature.

So I want you to look at this food taken out for a picnic on a warm, sunny day.

The ice cream has melted but the cheese has not.

And Laura says, "I wonder how I can find the temperature at which substances like cheese and ice cream melt?" So the children want to carry out an investigation to measure and compare melting temperatures.

What do you think their question could be? I'll give you five seconds to think about your answer.

Off you go.

So some of the questions that Laura, for example, has got, "At what temperatures do different materials melt?" Your questions may have been similar.

Now, the children chose some everyday materials in the solid state.

Andeep says, "We could put a small piece of each material on a piece of foil on top of a cup of hot water and wait for a few minutes to observe if it begins to melt." And he says, "If the material begins to melt, then we will measure the temperature of the water in the cup and record this temperature as the approximate melting temperature of that material." Laura says, "Great idea.

So if the material does not begin to melt, then we try a higher temperature water in the cup each time." Andeep says, "This will be a comparative test because the thing, or variable, that we are changing each time is the type of material." So they're going to be comparing.

We will try to keep other variables the same, such as the size and the mass of the material, the type of cup, and the amount of time the material is placed on the foil for.

Let's do a quick checking of your learning.

True or false.

All materials melt at the same temperature.

I'll give you five seconds to think about your answer.

Have a really good think back to the last lesson as well, to help you with this question.

Okay, I'll give you five seconds.

Off you go.

Fantastic.

Well done,.

The answer is false.

Now, why do you think that is? Is it because A, different materials have different melting temperatures, or B, the melting temperature of any material is not fixed?" Again, I'll give you five seconds to think about your answer.

Off you go.

Fantastic.

Well done.

The answer is A, different materials have different melting temperatures.

Now here is Task B.

It says, use Andeep and Laura's method, or your own ideas, to plan an investigation to answer the enquiry question, at what temperatures do different materials melt? You should include everyday materials in the solid state such as water, ice, candle wax, butter, chocolate, cheese, and kitchen foil.

So there are a number of ways you could choose to heat your samples.

So you could heat your samples on the lids of cups containing different temperature water, just like Laura and Andeep said, on kitchen foil on top of hot water bottles containing different temperature water, and in small foil cases floating in water baths of different temperature water.

So I'm going to give you some time now.

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

Off you go.

Fantastic.

Well done.

I asked you to plan an investigation to answer the enquiry questions, what are the melting temperatures of different materials? So number one, prepare a cold water bath.

Put a teaspoon of each material into its own small foil pie case.

Float the pie case in the cold water bath.

Observe for five minutes to see if any materials begin to melt.

Measure and record the temperature of the cold water.

And then I want you to repeat steps one to five with warm and then hot water.

And we will know that the melting temperature of each material is between the temperature of the water bath it melted on and the one that was cooler.

So now we are on to the summary of our learning today.

The process in which a material in the solid state changes to the liquid state is called melting.

The melting temperature is the temperature at which a solid changes to a liquid.

Different materials have different melting temperatures.

Scientists ask questions about the melting temperature of different materials and plan how to answer them.

Now, you have worked really hard today.

You've got a fantastic plan ready for our next lesson where we are going to be doing and reviewing.

Well done.