Lesson video

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Hi everyone.

Nice to see you.

Welcome to lesson six of this unit of work with me, Miss Emms. I hope that you've had a chance to watch lessons one, two, three, four and five of this unit of work, so that you're really prepared for this final lesson, where we get to bring together all of our knowledge.

And hopefully at the end of the lesson and later on, I might be able to see some of your pieces of work from this unit.

So let's get started straight away and I will show you what we're going to be doing.

So, in today's lesson we're going to learn about whether there are some changes that we can't reverse, okay.

And you are with me.

My name is Miss Emms. We've had to think in some of our previous learning about mixtures and how mixtures are created from two or more substances.

And we've also had to think in some of our learning about what happens when you mix a solid and a liquid together, okay.

Today we're going to be thinking are there some changes that we can't reverse.

The first thing we're going to do is we're going to do our star words.

So, our key important words that you'll need to understand in order to access the learning today.

And then we're going to move on to some recap questions.

After that we're going to have a think about two kinds of changes, reversible changes, and irreversible changes.

And finally, there will be an end of lesson quiz where you get to see all of the amazing things that you have remembered from the lesson.

So you're going to need a few things in this lesson.

You are going to need an exercise book or paper.

You're going to need a pencil and you are going to need your brain.

Your brain is ready.

Your brain is ready to go.

Give it a little massage like this.

Amazing, well done.

If you think you need to go and get your exercise book or paper and your pencil, then can you pause the video now and go and get those things? Off you go.

Right, you are ready.

So, first we are going to go through our star words.

Can you repeat after me? Star words, star words, star words! Great, well done.

Our star words, we have three today.

The first one is irreversible.

Your turn.


We're going to have a look at what that means really soon in today's lesson.



When something changes from one thing to another.

A change.

And finally, ingredients.


You will have heard that word before.

For example, when I'm making a cake, I'm going to need certain ingredients.

I'm going to need an egg.

I'm going to need some flour, some sugar, some butter.

These are my ingredients.

These are my? Great.

So, a quick recap now.

What were the three methods of separating that we learned about? So I'm going to help you out here because I'm feeling kind.

And I'm going to give you the first one.

So the first method that we learned about was sieving, okay.

So, we had a look closely when I showed you what it looked like to sieve one part of a mixture from the other part.

So it doesn't need to be in order.

But one of the methods that we learned about was sieving.

Can you remember the other two methods? Tell your screen if you can.

Did you get them? Separation by hand and magnetism and then sieving.

So, quickly I would also like you to match a method to the situation.

So separating flour and rice, which method would you use? Separating metal from recycling or waste.

Which method would you use? And separating stones from sand on the beach.

Which method would you use? Can you pause the video and write down one, two and three and the methods that you would use.

Off you go.


Well done.

So for the first one, separating flour and rice, you'd use a sieve, for the second one, separating metal from recycling or waste, you would use magnetism.

And for the third one, separating stones from sand on the beach, you would either use your hand or you would use sieving.



Moving on.

Before we think about irreversible changes, we're going to have a look at some examples of reversible changes.

It's important that we can say this really confidently.

Reversible changes.


So, freezing is an example of a reversible change.

That means that you can sort of undo the change.

You can go back.

For example, if you have some water and you put the water in the freezer, it turns into ice.

That's a reversible change because I can then melt my ice to get back to the water.

I've gone from water.

Water to ice.

And then from the ice to water again.

I've been able to reverse that change, okay.

So that's why we call it a reversible change.

Similarly, if I start with ice and I melt it to get some water, I can reverse that change because I can freeze the water again to get to ice.

So both are reversible changes.

An irreversible change is the opposite.

So have a little think about these ingredients here.



What do you think that I, Miss Emms, could make with these ingredients, if I had all of these ingredients in my cupboard? If I had some eggs, some flour, some sugar, maybe some butter as well or some oil and I had some sugar.

What could I make with these ingredients? Tell your screen.

You could make a.

You guessed it.

You could make a cake or some cupcakes.

Some delicious cupcakes.

Now, can I get the ingredients back if I wanted to? Could I get the egg back? Could I get the sugar back? Could I get the flour back if I wanted to? Yes or no? Show me yes or no.

You're right, I could not get those ingredients back.

That's an example of an irreversible change.

I can't reverse the change.

What about these delicious ingredients? I've got some tomatoes and I've got some pasta.

Perhaps there I've also got some onion and some garlic.

What could I make with these ingredients? Tell your screen, you could make a.

You're right.

I can make some sort of delicious meal with pasta and a sauce, a tomato sauce.

Can I get all of these ingredients back and in the state they were before they were used? Yes or no? No, you're right.

I can't get my tomatoes that haven't been cooked back once they've been cooked.

I can't get my pasta that hasn't been cooked yet once it's been cooked.

This is another example of an irreversible change.

Another example of an? Great, well done.

Now, what if I fried an egg? Do you think that I would be able, if I fried the egg like this in my pan, can I turn this fried egg back into a raw egg? Can I turn this fried egg back into a raw egg? Yes or no? No, I can't.

Cooking or frying the egg is an irreversible change.

It is an irreversible change.

Now another example is that when you burn wood, okay so like in a fire, it turns to ash and smoke.

When you burn wood, it turns to ash and smoke.

Can you get the wood as it was before, back again from the ash and the smoke? Yes or no.

Tell me.

No, you can't.

Burning wood, therefore is an? Irreversible change.

Well done.

So now you're going to do a sorting activity.

I would like you to draw and label two circles just like this.

So one circle that says reversible changes, reversible changes, and one circle that says irreversible changes.

I want you to pause the video now and on your piece of paper or in your book, draw your two circles and label them reversible changes and irreversible changes.

Off you go.

Pause now.


Well done.

Now I want you to have a look at these four examples of changes, burning, melting, freezing, cooking.

Your turn, burning, melting, freezing, cooking.

You can either draw the image or you can write the word or do both in the appropriate, the correct circle.

So if you think burning is a reversible change, draw the picture of the wood burning and write burning in reversible change.

If you think it's an irreversible change, draw the picture and write the word burning in irreversible change.

And I would like you to do this for all four of these changes.

Pause the video, good luck with your task and off you go.


Well done everyone.

So you should have completed that task now.

Let's have a look at the answers.

So our reversible changes were freezing and melting.

As we spoke about at the beginning of the video, if you freeze water, you can then melt it again.

And that will reverse the change.

And if you melt an ice cube, you can freeze it again.

And that will reverse the change.

So those are reversible changes.

Pause the video if you didn't get those two and you need to add them into your circle or tick if you did get them correct.

Don't worry if you made a mistake, you know by now that mistakes help your brain to grow and it helps you to become a better learner.

Pause to tick or fix.

And next, irreversible changes.

Burning, as we said, when you burn wood, it releases ash and smoke.

You can't get the wood back from the ash and smoke.

So it's an irreversible change.

And cooking, our examples of baking the cake or making the pasta dish with the sauce.

You can't get those raw ingredients back once you've cooked them.

So that's also an irreversible change.

Again, pause to tick or fix if you need to now.


Well done everyone.

And now it's time for your end of lesson quiz.

Don't forget, once the video has finished to complete your end of lesson quiz, to see what you've been able to remember from today's learning.

You have done such an amazing job.

This brings us, this is the last lesson of this unit and you have worked so hard.

You should feel really, really proud of yourselves.

If you'd like to share your work with Oak National, and this means any of the work that you've done in this unit.

So lessons one, two, three, four, five or six.

Please ask your parents or carer to share your work on Instagram, Facebook or Twitter by tagging @OakNational with #LearnwithOak.

It's been so nice to learn with you.

I hope you're feeling really proud of yourself.

And I think you definitely deserve a special kind of cheer.

We're going to do an awesome cheer for all the awesome scientists all across the country.

Like this, I'll show you, it goes like this.

Awesome! One, two, three.

Awesome! Well done everyone.

See you soon.