Hello, my name is Mrs. Mehrin, and I'm so excited to be learning with you today.

Today, we are going to be learning all about the physical properties of rocks and their hardness.

Welcome to today's lesson from the unit Rocks and Soils.

Your lesson outcome today is, I compare and group different rocks by investigating their hardness.

Now, I know that learning can sometimes be a little bit challenging, but that's okay because it means we're going to work really hard together and we're going to learn lots of new things.

Here are your key words for today.

I am going to be referring to these words throughout the lesson today, so you don't need to write them down.

However, if you would like to, you can pause the video now and jot them down.

Fantastic, and here are all of the definitions.

Again, I'm going to be referring to these throughout the video today, so you don't need to write 'em down.

However, if you would like to, you can pause the video now and jot them down.

Fantastic, well done.

Now, our lesson today is split up into two sections.

Let's begin with our first one, the physical properties of rocks.

We use different types of materials every day.

Let's take a look at these materials.

So we have wool, rock, plastic, wood, and glass.

Can you think of a word to describe the features of each one? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So you may have described wool as being soft, rock as being rough, plastic as being flexible, wood as being brown, and glass as being translucent.

These are all physical properties of the materials.

Different materials have different physical properties which we can observe and measure.

We can observe physical properties of rock by observing what the rock looks like, touching the rock to see what it feels like, smelling the rock to see what it smells like.

We can also observe physical properties of rocks by measuring.

Let's take a look at this rock face.

What could we measure? I'll give you five seconds to think about your answer, but if you think you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So we could measure the height of the rock face, the width of the rock face.

Let's do a quick check-in of your learning so far.

Which of these actions would help you find out some of the physical properties of rock? Could you A, feel the texture of the rock? B, I could find out where the rock came from, or C, I could look at the colour of the rock.

So let's remember the question is asking us, which of these actions would help you to find out some of the physical properties of rock? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So the answer is A, I could feel the texture of the rock and C, I could look at the colour of the rock, well done.

The hardness of the material is the physical property.

Some rocks are hard.

Can you name any hard rocks? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So we've got granite and marble here.

Some rocks are softer and they crumble easily.

For example, soapstone and chalk.

Let's do a quick check-in of your learning.

True or false? Hardness is a physical property of rocks.

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

Off you go.

Fantastic, well done.

The answer is true.

Let's see if you can justify your answer.

Is it because A, the hardness of rocks can be observed or measured or B, all rocks are hard? Again, I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

The answer is A, the hardness of rocks can be observed or measured.

Now, let's do some matching.

So it says here, match the rock to its physical property of hardness.

So you've got hard or you've got soft and crumbles easily.

So let's take a look at the different rocks we have here.

We've got soapstone, granite, marble, and chalk.

So match the rock to the physical property.

Is the rock hard, or is it soft and it crumbles easily? I'll give you five seconds to think about your answer, but if you do need longer, just pause the video here and return once you're done.

Off you go.

Fantastic, well done.

Let's see if you are correct.

So soapstone is soft and it crumbles easily.

Granite is hard.

Marble is hard.

And chalk is soft and crumbles easily.

So Sam says, "Pebbles are rocks.

"I want to make a bracelet out of pebbles I collected "on the beach.

"I need hard rocks "so that the bracelet will be hard wearing, "but I don't know which ones are the hardest." And Jacob says, "You will need to test each rock "to find out how hard it is." Can you think of a way to test how hard a rock is? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So Sam's friends have made some suggestions about how Sam could test how hard her rocks are, and I wonder if tho if any of these are what you have thought of as well.

So Jacob says that, "You could throw each rock "to see if it breaks." Izzy says, "You could weigh each rock to see how heavy it is "as heavy rocks are hard, aren't they?" And Aisha says, "You could scratch each rock with a nail "and see if it crumbles or leaves a mark." Which do you think would be the best way for Sam to test how hard each of her rocks are? I'll give you five seconds to think about your answer, but if you need to pause the video and you need to have another read through the suggestions, that's absolutely fine.

You can do that now and then you can return back to our lesson when you are ready.

Off you go.

Fantastic, well done.

So throwing a rock to see if it breaks is a test for brittleness, not hardness.

And weighing a rock just measures how heavy it is, not how hard it is.

So Sam says that she's going to take Aisha's suggestion.

So she says, "I will test each rock by scratching it "to find which is the hardest.

"If the rock scratches, or it crumbles, "this means it's not very hard." So here we have a picture of a nail and a rock, and the person has scratched the rock and you can see some of the rock has crumbled away, which shows us that that rock is not very hard.

Let's do a quick check-in of your learning so far.

Which statement about the hardness of rocks is true? Is it A, all rocks are hard.

B, some rocks are harder than others.

Or C, all rocks crumble when you scratch them.

I'll give you five seconds to think about your answer, but if you need longer, that's absolutely fine.

You can pause the video here and you can come back to our lesson when you are ready.

Off you go.

Fantastic, well done.

The answer is B, some rocks are harder than others.

Let's have a look at task A then, we are going to be planning a rock hardness test.

It says, "Discuss with a partner "how you could carry out a scratch test on different rocks.

"How are you going to compare rocks in a fair way? "What equipment will you need?" And it says, "To write a simple plan to show "how you will carry out your investigation "to test the hardness of rocks." So you are going to need some time now to carry out this activity.

So what I'd like you to do is pause the video here, have a go at this activity, and then return when you are ready.

Off you go.

Fantastic, well done.

So let's see if your plan was similar to this.

First, I will choose four rocks to test.

So you're definitely going to need more than one rock.

Four is a great number to choose.

Next, I will scratch each rock 10 times with a nail to compare fairly.

So again, you're choosing the exact number of times you're going to scratch each rock because if you only scratch one rock two times and another one 20 times, it's not going to be a fair test.

I will observe if the rock is marked after I have scratched it, and also if there is any dust from the rock on the paper towel.

I will put all the rocks that don't scratch into a group with the label "hard" and I will put all the rocks that do scratch into a group with the label "not hard".

It says caution because you do need to be careful when carrying out this experiment.

It says, "I will be careful when using the nail "to make sure I only scratch the rock." Now, we are ready for the second part of our learning.

You are doing so well.

So now, we are going to be grouping rocks by hardness.

Sam carried out a hardness test on her rocks by scratching each rock 10 times.

She observed how much of the rock crumbled and if there was a deep mark left on the surface of the rock.

So here, we have Sam's rock and she's scratching the slate with a nail.

Look at the images of Sam's rocks that she tested.

So we have granite, marble, sandstone, and chalk.

What do you think Sam's results show? So I'd like you to really observe, have really good close look at these pictures of the rocks that Sam tested.

What do you think her results show us? Off you go.

Fantastic, well done.

So Sam compares the harness of the rocks in her collection and we can see that the granite has not got any scratches on it and there isn't any dust, and it's the same thing with the marble.

The sandstone has left a mark, and with the chalk, you can see that it has crumbled and pieces of that rock are now on the paper towel.

So how could Sam sort her rocks into groups to show which rocks are hard and which are not hard? Again, I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So Sam could sort her rocks into groups like this one to show which ones are hard and which ones are not hard.

So we can see just by observing the picture that the granite and the marble have not left a mark and there is no residue, no dust from the rocks on the paper towel.

However, with the sandstone, you can see the scratch marks and with the chalk, you can see some of the chalk has crumbled away and is on her paper towel.

So do you agree with how Sam has grouped her rocks? Are there any other ways to group them based on Sam's results? Have a really good think.

I'll give you five seconds or you can pause the video here.

Off you go.

Fabulous, well done.

So Sam decides to test other rocks in her collection in the same way, and she takes photographs of her results.

Has the nail left a deep mark on the rock or has the rock crumbled? I'd like you to observe these two pictures really closely and see if you can answer that question.

I'd like you to pause the video here and then come back once you've done that.

Off you go.

Fantastic, well done.

So the limestone has, we can see that it's crumbled and it's there on the paper towel.

And here, we can see on the nice rock that actually there isn't any scratch marks and there are no crumbled bits either.

Sam is going to compare the harness of the rocks and then add them to her groups.

Let's do a quick check-in of your learning.

How do scientists show which rocks are similar and which rocks are different to each other? Do they A, create a list of equipment needed.

B, write a plan for a fair test.

Or C, sort the rocks into groups.

I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

They sort the rocks into groups roots.

Which of these rocks could be grouped together on the basis of their hardness because they are difficult to scratch with a nail? Remember, there could be more than one correct answer here.

So we have A, granite, B, chalk and C, marble.

I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

The answer is A and C.

So task B now.

It says to use your plan to test the rocks that you have chosen.

Remember to compare the rocks in a fair way.

You will need to count how many times you scratch each rock and with the same amount of force.

So make sure that you're not scratching one rock harder than the other.

Once you've tested your rocks, you're going to compare and group them to show your results.

And be really careful not to scratch yourself or anything else.

So make sure that you have really taken your time.

So I'd like you to pause the video here and have a go at that activity.

Off you go.

Fantastic, well done.

So you may have decided to scratch each rock 10 times with a nail, just like Sam did and observed to see if any of the rock had crumbled or if the rock had a mark on it from where you had scratched.

And you might have sorted your rocks into groups that looked like this using the criteria of hard and not hard.

So here, we have Sam's results.

So she has added some more rocks to her groupings.

She's got gabbro, gneiss and marble in the hard section.

She's got chalk, sandstone, and soapstone in the not hard section.

Now, let's go through the summary of your learning today, and you have worked so hard, so well done.

The physical properties of a material are its features that can be observed or measured.

Hardness is a physical property of many rocks.

Rocks can be compared and grouped on the basis of their hardness.

And remember that you can test for hardness in a rock by scratching at it with a nail to see if it leaves a mark or any of the pieces crumble just like in the picture here.

Now, you have worked so well today.

I am so proud of you.

You have tried your absolute best and you have learned so many new things, well done.