Lesson video

Hi there, everybody.

Welcome to your science lesson with me, Miss Emms. I am looking forward to teaching you all about shadows today, and I hope you're enjoying all of our science learning so far.

So let's get straight to it by going to our slideshow so you can see what we're going to be doing.

Okay, here we go.

So today our key question, the thing that we want to understand is how are shadows formed, okay? Shadows are something, a thing that you may have seen all around you before.

Don't know if you've ever thought carefully about how and why they are formed.

In today's lesson, we are going to follow this structure.

You should have already done a start of lesson quiz.

If you haven't done that, don't worry.

You can pause and you can exit the video, go back, do the start of lesson quiz, see how much you can remember from our previous lessons and then come straight back into the video.

Off you go and do that now if you need to.

Okay, thanks everybody, so you'll be ready now for the next part of our lesson.

We are going to then think about transparent and opaque objects.

Then we're going to think about shadows.

Then we're going to do a bit of an investigation as we normally do in our science lessons and finally you're going to complete an end of lesson quiz.

You're going to need three things in this lesson.

You're going to need an exercise book or some paper.

You're going to need a pencil and you'll also need your science brain to be switched on and ready to do lots of learning.

Can you give it a little massage to get it ready? Well done, everybody.

You might need some other things towards the end of the lesson for the investigation, but I will tell you about that as we get to that.

So to recap, and this is things that we've learned since the beginning of this unit all about light and dark.

So we know we've learned the terms light and light source, okay? We know that light is a type of energy that travels in a straight line from a light source.

And we know that a light source is an object, any object that emits, that gives out light, okay? We've also learned about reflection.

I'd like you to pause the video and I'd like you to tell your screen what happens when light hits an object.

Off you go.

Pause the video.

Okay.

Well done, everybody.

So reflection is when light bounces off an object.

Light travels in a straight line, hits the object, bounces off the object.

That's what's, and we can say that it's reflected off the object and then you may have told your screen that it travels in a straight line to the eye and it enters the eye through the puh, puh, puh? Pupil, well done, and then the eye sends signals to the buh, buh, buh? To the brain, and that's how we register that we have seen something.

A quick recap as we did last week on night and day, I'm going to ask the question.

You're going to say the answer to your screen.

Are you ready? Okay.

How many hours are there in a day? Tell me.

Amazing, 24.

Well done, pat on the back.

Why is it dark during the night? It's dark during the night because where we are on the planet, on the Earth, can't be reached by the sun, by the heat and the light of the sun, okay? We're facing away from the sun and it's light during the day because, tell your screen? Good, because where we are on the Earth is facing the sun and the light and the heat from the sun can reach us.

Lastly, the imaginary line that the Earth rotates on, it's called, it is called its, it begins with an ah, axis, well done, everyone.

Give me a virtual high 10.

Good job.

Okay.

So we've also learned as a recap in our last lesson about reflective materials.

So if a material's reflective, remember, like my jacket, it reflects light well and most of the light that hits the surface, that surface, bounces off.

For a non-reflective material, it does not reflect light well and some light bounces off the object but most of the light is absorbed, okay? So we learned the key words reflection and absorb.

Moving on to today, can you all go star words, star words, star words? Well done.

Shadow.

Your turn.

Today we're going to learn what a shadow is, okay? A shadow is formed when an opaque object blocks light.

Shadow.

Your turn.

Opaque.

We're going to learn what opaque and transparent mean today, opaque and transparent.

Can you say each of those words to your screen? Good job.

I'm going to hold off on the definition 'cause we're going to talk about that very shortly in the next few slides.

And finally, block.

You might have heard of that word being used in a different context.

If something gets in the way of something else, it blocks that.

It acts as a barrier.

So we are now going to have a think about opaque and transparent objects.

If an object is opaque, if it's made of an opaque material, then you cannot see through that material.

If an object is transparent or the material of the object is transparent, then you are able to see through that material and that is because if an object is opaque, for example, my book, the object blocks the light rays from the light source.

So I'd like you to imagine, I'd like you to imagine that the sun is up here and the light rays are coming from the sun.

If an opaque object blocks those light rays, they can't get past, then a shadow is formed because the light rays can't travel through the object.

That means the object is opaque.

But if an object is transparent, say the word, the light rays are able to travel through that object.

Therefore, you can see through the object.

For example, I've got a plastic Tupperware that I can see through and you can see me as well if I hold it here.

We're going to have a look further in a minute at different types of opaque and transparent.

Before we carry on, I wonder can you tell your screen an object that you can see now that you think might be opaque? Great suggestions.

Can you tell your screen now an object that you think might be transparent, that you can see through? Great ideas.

Well done, everybody.

So let's read this passage together and then you're going to answer the retrieval questions at the bottom.

I'm going to read it first and then I'm going to let you pause to read it by yourself.

Some objects allow lights to pass through them, while other objects do not.

Transparent objects, such as glass, let almost all of the light rays pass through them.

When you look at transparent objects, they look clear and you can see straight through them.

Opaque objects and materials, such as metal, do not allow any lights to pass through them.

You cannot see through opaque objects.

So I would like you to pause now.

I'd like you to read that again to yourself and then I'd like you to answer these two questions, can light pass through opaque objects? Write down one and then yes or no.

Two, can light pass through transparent objects? Write down two and yes or no.

Pause the video and complete that task now.

Okay.

Well done, everybody.

So you should have said that light cannot pass through opaque objects.

So one was no.

You should have said that light can pass through transparent objects.

So two was yes.

Okay, let's move on.

Look around you.

What objects can you see that are opaque? What objects can you see that are transparent? Make a list in the table below.

So you need to draw a table just like this.

Don't worry about these two images.

Put two columns.

The first one has the title opaque.

The second one has the title transparent.

Pause the video and just draw the table.

Don't write any objects down in it yet.

Off you go.

Wonderful, well done, everyone.

So you've drawn your table.

You're ready to do a little bit of investigation.

So this is the test.

Remember, if you can see through the object, the object is tuh, tuh, tran, transparent if you can see through it because light rays can pass through.

So I would write, let me do a check, can you still see me? I can still see you.

So for the glass, I'm going to put it into transparent.

I would write glass here.

I'm going to pick up another object.

Hmm.

I am going to pick up, I'm going to pick up a piece of paper.

I'm going to see if I can see through the piece of paper.

I can't see through the piece of paper at all.

Light rays can't pass through the piece of paper.

The piece of paper, well, most light rays can't pass through the piece of paper.

It blocks most of them.

The piece of paper is oh, it's opaque.

I wonder, can you go around your home or the area that you're sitting in at the moment? Can you make a list of some opaque objects and some transparent objects? Off you go.

Have fun.

Okay, well done, everyone.

I hope you managed to find some examples of opaque objects and transparent objects.

This is what you could have had.

You could have had lots more but I had to think about some that I had in my house, and when I did the test, the experiment, I found that paper was opaque.

Wrong sheet.

That's my book.

Paper was opaque.

The book was opaque.

Clothing was opaque.

So I couldn't see through clothing or things that were made out of fabric.

For example, this cushion, I can't see through it.

It's opaque.

And cardboard I found was also opaque.

Things I found that were transparent were my glass, the window, windows have to be transparent, don't they? 'Cause you need to be able to see through them.

A plastic box that I had and some Tupperware that I had that was opaque, and also a plastic bottle.

Now, this part made out of paper is not opaque whereas the top part made out of plastic is opaque.

I can see through that.

I can't see through that, okay? I wonder what you found.

So now we're going to move on to learning about shadows and why shadows are formed.

We're going to read this passage together now.

I'm going to read it first.

Then we'll pause and you'll read it by yourself.

Listening cap.

So, shadows are made when an opaque object blocks light.

Can you all say block? Your turn.

Gets in the way of, obstructs, is a barrier.

Shadows are made when an opaque object blocks light.

Light rays travel from a source in straight lines.

Show me your straight line.

If an opaque object gets in the way, it stops light rays from travelling through it and this results in an area of darkness appearing behind the object.

The dark area is called the shadow.

It's called the? Great, during the day, the light from the sun can cause shadows when it reaches an opaque object.

So let's have a think about this man.

He's standing in the light.

He's probably standing outside.

Therefore, the sun is the light source.

Now, the man, mostly he is blocking the light, okay? You can't see through a person.

You can't see through his clothes.

You can't see through the box, okay? Everything is opaque.

Therefore, what's happening is he is blocking the light rays from the sun.

What's he doing, he's? Great, and that is creating a sh, a shadow, the dark area where the light rays have been blocked, they didn't get through, and a shadow is therefore formed.

I'd like you to pause and I want you to read that again to yourself out loud so you understand really clearly.

Can you go pause now? Okay, so just to recap, I want you now without that help on the screen to tell your screen how are shadows formed? How are shadows formed? Pause the video, and as if your screen is your teacher, tell your screen how are shadows made? Shadows are made when, now you pause and tell your screen.

Great.

Well done.

So shadows are made when an opaque object blocks light.

Let's say it again.

Shadows are made when an opaque object, one that you can't see through, blocks light.

Tell your screen again.

Shadows are made when? Super, well done.

Can you guess the object that each shadow belongs to? You might find this a little bit easy but I thought I'd put it on there anyway to get us thinking about what objects these two shadows belong to.

Point to this one.

What do you think these shadows belong to? To? Yeah, to people.

This person is a bit taller, isn't he or she? This person is a little bit shorter.

And this object, I think the shadow, I think this object is a, a tree, exactly.

It's not the tree itself.

It's because the tree is mostly, is opaque.

Okay, so here, that is where the tree, the opaque object, blocked light, okay? You can see here that it's getting a little bit lighter and less of a block shadow.

That's because as the trees get thinner at the top, more light is able to pass through, okay? But you can still see that light is blocked and therefore there are shadows of the branches.

Now, for our investigation, second investigation, I want you, now, it's a bit tricky if it's not sunny at the moment where you are.

Where I am at the moment, it's not very sunny.

It was sunny earlier today.

It's not very sunny anymore.

But you should still be able to have a go at this experiment.

It doesn't need to be fully sunny for you to see shadows because there is still light coming from the sun, the light source, unless the clouds are blocking that sun so much that we don't see, we can't see many shadows, in which case it's going to be trickier for you to do.

Maybe you could save it for when there is a little bit of sun.

You need to see what objects can find, what objects can you find around you that make a shadow.

So when there is a bit of sun, choose some objects, so I might choose my book, I might choose this cup, some paper, I might choose anything that I think is opaque and that will make a shadow.

I'm going to test as well.

I would take some transparent objects too.

If you're taking glass, you need to ask a parent or carer.

And see if they create shadows.

Go outside and see if you can create a shadow with different objects and write down the ones that do create a shadow.

Off you go.

Have fun.

Okay, so you may have, you will have hopefully found that if you did it now, you might be saving it for later, that anything that was transparent did not create a shadow.

Things that were opaque made a shadow because they blocked the light rays from the sun.

Now, we're coming towards the end of the lesson and this question should make you think a little bit harder.

Have a look at the picture.

Hmm, why can we not see the flame in the shadow? Why can we not see the flame in the shadow? Why can you only see the matchstick and the hand? Pause the video.

Have a think and tell your screen.

Great job, everyone, for thinking so hard.

You can see the shadow of the matchstick because this, the matchstick, is an opaque object that's blocking the light of the flame, okay? But there's nothing, there's nothing blocking the light of this, of the flame, so we can't see its shadow, okay? There's no opaque object that is blocking that light so you can't see the shadow of the flame.

You can only see the shadow of the matchstick because that is an opaque object that's blocking the light of the flame.

Okay.

Well done, everybody.

Really impressed with your learning today.

It's now time for you to complete your end of lesson quiz.

So when I finish, when my video ends, it's time for you to go to the next activity, see how much you can remember from this lesson, and have a go at your end of lesson quiz.

Amazing job today and if you'd like to share any pictures of what you've learned, please do remember to ask your parents or carer first and see if they can share your work on Twitter @OakNational with hashtag #LearnWithOak.

Okay, everybody, I will see you next time for more science learning.

Bye.