Lesson video

Hello there.

My name is Mr. Wilshire, and in this lesson, we're going to be looking at light sources.

The outcome for this lesson is I can identify and name natural and human-made light sources.

As always, there are some key words for us to consider as we progress through this lesson.

The first is light source, then human-made.

Finally, natural.

Don't worry if you're not too sure what some of these words mean.

The definitions have appeared on the screen for you now, so if you need to, you can pause the video now, have a recap and then restart when you're ready.

The first section of this lesson is called human-made light sources.

Sam and her class are on a school trip.

They've gone to a local cave to explore some different types of rock.

Here's Sam and an example of the cave.

She says, "I don't like being in this dark cave.

I want to be able to see where I'm going." I wonder in this case, what would help Sam to see? Do you have any suggestions? Pause the video now and discuss.

Restart when you've done that.

So, what did you discuss? Have you thought of anything that could help Sam to see? Is there some way that we can light up this situation? Hmm, let's find out more.

Sam needs light to be able to see.

Here you can see an image of an entrance to a cave.

Light comes from lots of different places.

We call something that produces and gives out light a light source.

I wonder, now that we know this information, what kind of light sources could the children use to help them to see inside this dark cave? Think of some different suggestions and restart the video when you've discussed.

What light sources did you come up with? Is it possible to take the sun into the cave? Hmm, not really.

Maybe you've chosen to take the torch on a phone or other mobile device.

The children could use a light source, such as a torch or a lamp inside the cave.

Here you can see other people exploring through the cave and there's plenty of light sources around.

Sometimes in caves, they've run lots of cabling inside.

This enables people who are mining or caving inside or just exploring to be able to see everywhere, as they can plug in different lights.

I wonder what light sources you can see around you now.

Hmm.

Take a really good look around where you are right now and decide what light sources can you see.

What light sources did you find? Well, I know that I've got on my wrist, I've got a watch and that can light up.

I've currently got these lights, and look, if I cover them up, you can see I go a little bit darker.

There's plenty of light sources in my room.

I wonder if you've got anything similar.

There may have been some of these types of light sources in the classroom or the room that you're in.

There are many different types of light sources, both indoors and outdoors, and we use them to help us to see.

You may have a bedside lamp that looks a bit like this.

You may have seen some street lights outside your home.

Maybe even you've got a ceiling light that looks a little bit like this.

Inside all of these appliances are different types of bulb that light up.

Let's stop and think.

What is a light source? Is it something that produces and gives out its own sound? Is it something that produces and gives out its own smell? Or is it something that produces and gives out its own light? The correct answer here is C, something that produces and gives out its own light.

Now, some light sources are human-made.

I wonder what you think this means.

Have a quick think now.

Restart the video when you've done that.

What does that mean, human-made? You may have also heard the term manmade.

It means that someone has made it, a human has had to make it.

It's not a naturally occurring type of light source.

Here's two examples.

You can see some disco lights.

You may have these in your school hall or you may have seen them somewhere else.

A ring light is also something that's been human-made.

Look, I covered it up earlier to make it a little bit darker in here.

A ring light has been made by a human.

I wonder what other sources you came up with.

Here are some more examples.

Light sources that are human-made have been created by humans.

You may have had some examples, like the torch on a phone or even a head torch, and what about car lights? All of these things have been made by humans to enable us to see in the dark.

Human-made light sources often use electricity to produce light.

You can see two examples here, flood lights in a stadium and a nightlight that this child's able to hold.

Some human-made light sources use different ways of generating electricity to produce the light.

You can see here an example of a windup torch, and also a solar powered garden light as well.

There's a windup torch there.

It's got a little handle that you need to spin and that will generate the light from the electricity that's made.

The solar power here charges the batteries inside this solar light, and then of course the light comes on when it's dark outside.

Stop and think.

A human-made light source means it is used by humans.

What do you think? The answer here is false.

It's not used by humans.

How can we justify our answer? Is it because human-made light sources, light torches, car lights are lamps are made by humans, or is it that all light sources are human-made? The answer here is A, all light sources are not human-made.

Some are naturally occurring.

Here is the first task.

You need to place one object at a time into a box with a secure lid, then you're going to need to look through a small hole in the side or top of the box to observe which objects produce light.

Here you can see an example of the box with a hole in the lid.

There is the hole pointed out to you.

Here are some objects that you could test inside the box.

The objects are aluminium foil, a mirror, an electric light switched on, a tube of glitter, a tree bauble or decoration, a crystal, a torch which is switched on, and a phone or electronic device, also switched on.

Before you put them into the box, have a really good think.

Which of these do you think are a type of light source? Do they emit any kind of light all by themselves, or do you need to do something to them first to enable them to give you the light? Try putting these items into a box and then take a peep through the hole.

When you've done your predictions, you can then use your observations from putting the items into the box to identify and group the objects into those which are light sources and those which are not light sources.

You can then tell a partner why you've grouped them in this way.

Use the table here to help you clarify what you mean.

Best of luck putting the items inside the box and peeping through the hole.

See you in a moment.

Well done for completing that task.

Your results might look similar to this.

Don't worry if they're not though.

You may have found something different.

So the light sources are the electric tea light, the torch and the phone or the electronic device, all of those things that need to be switched on, don't they? Not a light source, however, the aluminium foil, the mirror, the tube of glitter, the tree bauble or decoration, and the crystal.

All of those items there did not emit any light when we peered through the hole in the box.

Tell a partner why you grouped them in this way.

I wonder what kind of discussions you had.

Here's Jacob and he says, "Well, I couldn't see the foil, mirror, glitter, bauble and crystal in the dark box.

These objects are not light sources.

I could see the electric tea lights, and the torch, and the phone easily because they produced light.

They lit up the inside of the box.

These objects are light sources." So being able to light up the inside of the box was very important here, wasn't it? That's the way that we know that it's a light source.

Well done for completing your task.

The final part of this lesson is called natural light sources.

We often use human-made light sources at night when it's dark.

Here you can see two examples.

There's a lighthouse there to shining a light out into the sea, and there's also a searchlight which someone is holding in their hand.

Wow, that's a very powerful searchlight there, isn't it, that they're holding.

Are all light sources human-made? Have a good think here.

We've answered this question already during this lesson.

I wonder if you've been listening.

Restart the video when you've discussed this.

So are all light sources human-made? What did you think? The answer is no.

Some light sources are not made by humans.

We call these natural light sources.

Although humans do make a lot of different light sources, doesn't mean that all light sources come from humans.

I wonder if you know any natural light sources though.

What do we mean by natural? Have a discussion and restart the video when you've done that.

So, what things did you think of? What are natural light sources? I know that a ring lights like in my room here, that's not natural.

The lights in the ceiling, they're not natural either.

On my wrist, my watch, that's not natural.

All of those things have had to be made by humans.

What kind of natural light sources are there then? Well, stars are one just example of natural light sources.

Remember, our Sun is also a star.

They're not made by humans, and they produce and give out light naturally.

We don't need to switch it off and on again, do we? A bright bolt of lightning from a lightning strike will occur naturally as well.

This also lights up the area.

This is a naturally occurring light source.

Fire is also a light source.

Do you think that fire is a human-made or a natural light source? Hmm, have a think and a discussion.

Restart when you've done that.

Well, what did you think? Is fire naturally occurring? A forest fire or fire caused by lightning striking can occur naturally.

That's when lightning hits the ground and starts to set the vegetation that's there on fire.

This can spread very, very quickly, especially if it is very hot somewhere.

Some fires, however, are started by humans, like a match.

If you strike a match against a matchbox, it will then light and you're able to light something else with it, like a candle.

You could also use this match to light your very own campfire.

Then you could have a go cooking something or maybe use it to roast some marshmallows.

Campfires are also a really nice thing to use to keep warm and give yourself some light where you might be camping somewhere that it is particularly cold or particularly dark.

Animals such as glow worms and some types of jellyfish can also produce and give out light.

These are all natural light sources.

They've not be made by humans.

Here, you can see some glow worms, and there you can see a jellyfish.

I've never seen anything like this before, so it must be in certain countries that this happens.

But I have seen plenty of pictures and videos, especially of different things lighting up either the water or the vegetation.

How fascinating.

I wonder which natural light source produces light so that we can see during the daytime though.

What do we mean by that? What natural light source gives us enough light to see during the day? Discuss.

What natural light source did you think of? The Sun.

The Sun is our main natural light source.

Here you can see an image of it.

Now, our earth in comparison is very, very small.

Sofia says, "We must never look directly at the Sun because it can damage our eyes." Very good, Sofia, yes.

Even if you're wearing sunglasses or any sort of eye protection, if you're looking at the Sun for periods of time, it can slowly damage your eyes, so it's a very good idea not to.

It's also far too bright, so I have no idea why you would want to.

Don't look at the sun.

It's not a very good idea.

Aisha says, "Is there a switch that turns the Sun on and off to give us light?" Here you can see an image of daytime.

Sofia says, "The sun is always producing light.

When our part of the planet is facing towards the Sun, it gives us light and we call this daytime." Of course.

So our planet is constantly orbiting the Sun, and while it's doing that, it's also rotating, isn't it? So that rotation is giving us our day and our night cycle.

Even though we can't see the Sun in the sky, doesn't mean that it's not there.

Is there anything in the sky at night that gives us a clue that the Sun might still be shining? The Moon is one such example.

The face of the Moon is lit up by the Sun, and it's reflected down onto earth.

So I wonder, is that also a type of light source? Hmm.

Consider that while we move on.

Stop and think, which of these is a natural light source? Is it a torch, the Sun or fairy lights? The correct answer here is the Sun.

The Sun is a natural light source.

So here's what we considered before.

Laura says, "I think we have another natural light source that we see at night." Yeah, she's right.

You can see the Moon at nighttime, can't you? She says, "I've seen the Moon shining brightly at night, so it's got to be a type of light source." Hmm, what do you think? Is it a light source? Do we switch the Moon off and on again, or does it produce its own light? What do you think? Discuss.

So what did you think? Is the Moon a type of light source? The Moon is made from rock and dust.

It does not produce its own light.

It appears to shine, but it's not actually a light source.

Jun says, "I disagree with Laura.

The Moon might look like it's a light source, but it's not giving out any light." We see the Moon from Earth because light from the Sun shines on the Moon.

This is exactly what I said earlier, isn't it? Laura says, "Wow, so the Moon is not a light source.

It only looks like it produces light, but it does not." Of course, the Sun shining on the Moon's surface can then be reflected back to us by the Moon.

The Moon isn't a mirror, but it is made up of lots of dust, and as the light shines onto the Moon and lights up the surface, we can see that happening from Earth.

The Moon then acts as a bit of a nightlight in the sky for us.

The Sun is the thing that is shining on it, giving it the sort of effect that looks as though it is a light source when we know that actually it's not.

The Moon does not transmit any light.

Stop and think.

Who do you agree with here? Aisha says, "The Moon is a human-made light source." Alex says, "The Moon is not a light source," and Lucas says, "The Moon is a natural light source." Who do you agree with? Alex is correct here.

The Moon is not a light source.

So here's task B.

Sort these light sources into human-made light and natural light sources.

Have a little look through each of the images here.

The street lights and light bulbs, fire and jellyfish, stars and glow worms, and fairy lights and the Sun.

Sort them into two sides, natural and human-made.

Best of luck with your task.

See you in a moment.

How did you get on? Were you able to sort them out and maybe you put them into a table a little bit like this? Human-made light sources are street lights, fairy lights, light bulbs and fire.

Natural lights are, natural light sources are stars, the Sun, jellyfish and glowworms. But Alex says, "Well, fire could go in either column, and some fires begin naturally and others are started by humans." That's a very good point there.

I wonder, did you choose a column for the fires to go in, or did you put it in between the two? It's up to you.

Let's summarise our lesson.

A light source is something that produces and gives out light.

Light sources can be natural or made by humans.

The Sun is our main natural light source, and the Moon is not a light source because it does not produce its own light.

Well done for completing those two tasks there.

Hopefully you've got a good idea as to the type of light that is created by humans, and the type of light that we find naturally.

If there were no naturally occurring fires, I wonder if we would've ever have found fire as a species to be able to warm things up and light our days.

If there was no naturally occurring fire, I wonder if humans would've been able to find it eventually or not.

What do you think? I've been Mr. Wilshire.

Thank you very much for listening.