Hi everyone, my name is Ms. Panchal, and today we're going to be comparing different types of salt.

We are going to be comparing table salt and rock salt.

And this lesson is part of our bigger unit of learning on Materials.

So we're going to look at lots of examples to help us understand this learning.

Let's get started with a lesson 'cause we've got lots to do.

So the outcome for our lesson today is I can use a hand lens or microscope to observe and compare rock salt and table salt.

So here on the screen we've got some keywords that we are going to be using in our lesson today.

So we've got table salt, processed, salt mines, rock salt, and microscope.

So what I'd like you to do is pause the video here and first of all read the definitions out to yourself.

And then I'd like you to with your partner, work together in reading out the definitions to each other.

Once you've done that, click play and we'll start the lesson.

Good reading everyone, well done.

So our lesson today is split up into two parts.

So the first part of our lesson, we're going to be focusing on table salt.

And then the second part of the lesson we're going to be focusing on salt mines.

So let's get on with the first part of the lesson.

So Alex noticed his mum putting salt on her food at dinnertime.

He has seen people use salt in cooking too.

But Alex says, I wonder if the salt we use on our food is the same salt we use for cooking.

What do you think? So pause the video here, have a discussion with your talk partner.

Is the salt we use on our food the same as the salt we use for cooking? What do you think? Great idea everybody, well done.

So there are several different types of salt actually, so let's look at them.

So the salt people put on their food or in their cooking is usually a type of salt called table salt.

Alex's mom said it is called table salt, because it is often kept on the table in a salt shaker and used on our food.

It has other names too, such as common salt or kitchen salt.

Scientists also call it sodium chloride.

So table salt is used to make the flavour of foods stronger, and it is used for lots of other things as well.

Do you know any of them? So pause the video here, have a little think in your heads on your own and then share your ideas with the people around you.

Do you know any different other uses for table salt? Brilliant, well done everyone.

So in baking, table salt strengthens dough, making bread firmer and chewier.

And in cooking table salt is often added to water to raise the boiling temperature, allowing food to be cooked faster.

So table salt can actually be used for other purposes as well.

Before people had fridges, table salt was often used to preserve food to help make it last longer.

And when salt is added to food, it draws out moisture and lessens the growth of bacteria which can make us ill.

So a long time ago when they didn't have fridges, they didn't have freezers, they used salt and covered things like meat with lots of salt in order for it to last longer to preserve the food.

So that's something.

Another use of table salt a long time ago, it's not really used for that purpose very much anymore just because we have fridges and freezers now, but a long time ago, that's what it was used for.

Let's do a check of our learning.

What is the name given to the salt people usually put on their food or in their cooking? A, bottle salt, B, cooking salt, C, table salt.

Brilliant, the answer is C, table salt.

Let's move on.

So table salt can be obtained through two main methods.

So the first one is mining underground salt deposits, and the other one is evaporating sea water.

So you've got two pictures here we've got a salt mine and we also got evaporating sea water.

The salt we get from the sea is called sea salt.

And sea salt is produced naturally when water from oceans or salt water lakes evaporates.

Sea water is channelled into shallow ponds known as salt pans, where it is left to evaporate naturally.

This often takes several months but leaves behind salt crystals where the salty water once was.

So the salty water is there, but then the water evaporates leaving the salt left behind.

Let's do a check of our learning.

Which one of these is a source of table salt? A, plants, B, animals, C, sea water, D, space.

Which do we think is the correct answer? Brilliant, the answer is C, sea water.

Now let's move on to the first task of this lesson.

So what I'd like you to do is make a salt water solution like sea water.

So first of all you need to add two teaspoons of table salt into a beaker of water, and then I'd like you to stir until it's dissolved.

Then I'd like you to use evaporation to recover the salt from the water.

So you could use the oil burner method, which we'll be look at on the next slide.

Or you could leave a saucer of salt water in a sunny position for a few hours.

Then I'd like you to record your observations as notes.

And if you'd like to, maybe you can draw some pictures or take some pictures to help you with your observations.

So let's have a look at the evaporation method here to recover the salt from the water.

And this is the oil burner method.

So first you would need to pour a small amount of salt solution into the top of an oil burner and light the candle, and then continue heating until the liquid evaporates.

Then blow out the candle and let it cool.

So here is an image of the oil burner method to help you with your task.

So pause the video here, have a go at this task, and I'm really looking forward to hearing your observations.

Off you go.

Excellent work everybody, well done.

I can see you've worked really hard to write down some ideas of the different observations you had made, but also some of you have taken some great pictures as well.

So let's look at an example answer.

We put a tablespoon of salt solution in a warm, sunny place, and left it until the water had evaporated.

The water evaporated and we could see the salt crystals left in the saucer.

We also managed to do this with sugar solution to recover sugar crystals.

So we can see here, they've actually made their salt solution but they've left it in a warm sunny place and the warm sunny place has allowed the water to evaporate and the salt crystals were what was left.

So here we can see the saucer with the salt crystals after the evaporation.

Did your dish look similar? Well done for having a good go at this task everybody, I'm so impressed.

So we've finished the first part of the lesson, where we've looked at table salt.

So we're now going to be thinking about salt mines.

So let's get on with the second part of the lesson.

So Alex is learning about where the table salt we use on our food comes from.

Alex says, I know that sea salt can be harvested from the sea, but my book about rocks says that table salt mostly comes from under the ground.

Is that true? Do you know? So pause the video here and have a discussion with your talk partner.

What do you think about what Alex is saying, is it true? Brilliant ideas everybody, well done.

So most table salt is often processed from salt deposits deep under the ground in salt mines.

In the mine it is called rock salt.

So here we've got an image of a salt mine, and in the mine it's called rock salt.

Alex has seen rock salt used in gritting lorries and grit bins where the salt is spread to make roads and paths less icy in cold weather.

So often in the winter season when the weather has been predicted that it's going to snow, or be quite icy, you'll see these gritter trucks out maybe late in the night and they're going to be spreading salt on the grounds, on the roads and on the pathways to ensure that they are not as slippery for people driving and people walking when it is snowy but also icy as well.

The rock salt used for gritting would not be safe to eat.

Most table salt begins as rock salt, but it is processed to turn it into table salt.

First the rock salt is dug up from the mines and this salt is in large lumps which need to be crushed into smaller crystals.

Then the rock salt crystals are dissolved in water and filtered to remove any dirt or other unwanted solids.

So we can see here the rock salt is crushed and then is dissolved in water.

Alex says, won't the salt get stuck in the filter? What do you think? Pause the video here, have a little bit of thinking time on your own, and then share your ideas with your partner.

Won't the salt get stuck in the filter? What do you think will happen? Great ideas everyone.

So salt is soluble and forms a salt solution when dissolved in water.

So the word soluble means it will dissolve in water.

The solution including the salt, passes through a filter which removes the dirt.

So the rock salt is crushed, dissolved in water, and then it is filtered.

The salt solution is heated and the water evaporates leaving salt crystals which are left to dry.

This is similar to the task in the first part of the lesson.

So the salt solution is then heated, and the water then evaporates leaving the salt crystals left on the tray.

After drying, extra ingredients are added to the salt, and some of these are added because they are good for people's health, and some are added to stop the salt forming clumps in the packet.

So once you have the dry salt crystals, often other ingredients are added onto it as well.

Alex says, I had no idea that all of this happens before my mom adds salt to her meal.

So often we think we just see, you know, salt in a tub, we all we buy from the supermarket, but actually it's had a long process to get to where it actually is.

Alex collects a small sample of rock salt from the grit bin in his school grounds, and pours some table salt onto a plate.

So Alex here has collected some rock salt, and also some processed table salt.

Alex says, isn't it amazing that one is used to produce the other? Alex decides to compare the salt samples to make and record observations.

And remember observations are things that we can see.

Alex says salt crystals are quite small so I think I will need equipment to observe them closely.

Can you decide which equipment will Alex? So there are different types of salt can be observed and compared using a hand lens or microscope.

So we've got an image of a hand lens here and we've also got some images of different types of microscopes.

And Alex will need to use this equipment to help him look at the salt crystals really carefully.

Let's do a check of our learning.

Where is rock salt found? A, in sea water, B, in underground mines, C, inside volcanoes.

Which do we think is the correct answer? A, B, or C? Great, the answer is B, in underground mines.

Let's do another check of our learning.

Which of these could you use to observe and compare different types of salt? A, telescope, B, hand lens, C, a microscope, D, a television? I'll give you a clue here, there's two things that you could use.

Excellent, so you could use a hand lens or a microscope.

So these two things would help you observe and compare the different types of salt because you'll need to be looking really, really closely and carefully and actually magnify the salt crystals that you can see, because the crystals are very small.

Super job, really well done.

So let's move on to the next task for this lesson.

So I would like you to use a hand lens or microscope to make observations of table salt and rock salt.

Draw and label a crystal of each, and note any similarities, or differences.

So when we're talking about similarities, we're thinking about what things are the same.

Are the size of the crystals the same, the shape, the colour? And when we're thinking about differences, what things are different, why might they not be the same? So when you are doing your notes, I want you to consider the size of the crystals.

Are all of the crystals the same size, or are they different sizes? I would also like you to consider the shape of the crystals.

Do they all have a similar shape, do they have different shapes, are they different sizes? And also I want you to consider the colour of the crystals.

So when thinking about the colour, we need to think about, are all the crisp salt crystals within table salt the same colour? And within rock salt, are they all the same colour? And what are the similarities and differences between the table salt and the rock salt? So pause the video here and have a go at this task.

I'm really looking forward to seeing all of your drawings and your notes.

So pause the video, have a go at this task, and we'll go over some examples and observations very soon.

Off you go.

Brilliant observations everybody, well done.

I can see you've done really fantastic drawings, but actually you've written some really brilliant notes as well.

So let's go through some examples.

So the task was to use a hand lens or microscope to make observations of table salt and rock salt.

You then needed to draw and label a crystal of each, and notes any similarities or differences.

So you may have noticed some of the features shown in these photos.

So the first one we've got is table salt, so we can see a cuboid shape, white, small crystals, whereas in the rock salt, we've seen less regular shapes, brown and speckly, and there were a lot larger crystals.

Did you get similar observations, or did you get some different ones? Well done by having a good go.

So we can see that under a microscope here or hand lens that table salt and rock salt are very, very different.

They are both types of salt, but actually, they have many, many differences.

So in terms of the shape, this table salt is more of cuboid shape, whereas actually the rock salt has less irregular shapes and actually the different crystals are different shapes.

And in terms of the colour, we can see the table salt is a white colour, whereas the rock salt has a more brown and speckly colour.

And in terms of the size of the crystals, we can see that table salt has much smaller crystals compared to the rock salt, which has much larger crystals.

So I hope you had a great time doing this task, and that you had experience of using a hand lens or a microscope.

Well done everyone.

So we've come towards the end of our lesson now, so let's do a summary of our learning.

The salt people put on their food or in their cooking is usually a type of salt called table salt.

And table salt has a wide range of uses.

And we learned that also it can be used in baking as well.

Table salt can be obtained through two main methods, mining underground salt deposits, and evaporating seawater.

In addition to that, we've learned that there are different types of salt, and they can be observed and compared using a hand lens or microscope.

So we know that different types of salt crystals can be quite small and it's difficult to see with our naked eye.

So we sometimes need to use things to help us, for example, a hand lens or a microscope.

And that helps us to zoom into the salt crystals really carefully and we're able to observe them much closely.

Now, a huge well done to you all for your work today.

I'm so impressed with all of the work that you've produced, and using the hand lens and microscope, I can see you worked really hard to use that equipment accurately, and you were able to make really good observations on the different salt crystals.

Now I hope you have a great rest of the day, and I'm sure I'll see you in the next science lesson.

Bye-Bye.