Lesson video

Hello and welcome to today's lesson.

My name is Mrs. Mehrin and I'm really looking forward to learning all about light sources, and light reflectors with you.

Welcome to today's lesson from the Unit Light and how it travels.

Your learning outcome for today is I can describe the differences between light sources and light reflectors.

Now we are going to be using some of our previous learning all about light, how it travels and light sources as well.

Now, I know that learning can be a little bit challenging sometimes, but that's okay because we are going to learn together, and we are going to learn lots of fabulous new things.

Let's begin.

Here are your key words for today.

Now, you don't need to jot these down because I am going to be going over them throughout the lesson, but if you'd like to, you can pause the video here.

Off you go.

Fantastic, well done.

And here are all of the definitions for those words as well.

So again, I am going to be referring to these throughout the video, so there's no obligation on you to write these down, but if you'd like to, you can pause the video here and jot them down.

Fantastic, well done.

Now your lesson is split into two sections today.

Let's begin with the first one, light sources and light reflectors.

So light can come from many different sources.

Some light sources are natural and some are made by humans.

So here we have lightning, which is a natural light source, and we have a computer monitor, which is a light source that is made by humans, so it's manmade.

Now how many different light sources can you name? I'll give you five seconds to think about as many as you can, or if you want to make a list, or you need some more time to think about your answer, you can just pause the video here.

Off you go.

Fantastic, well done.

Now Jun has made a list of things that he thinks are light sources.

He says "The sun, the moon, a candle, a metal spoon, a mobile phone" and he thinks all of those are light sources.

And he says "All of these objects give out light or shine, so they must be sources of light." Are there any objects on his list though that you don't agree with? I'll give you five seconds to think about your answer, but if you need longer that's absolutely fine.

Just pause the video here and have a go.

Off you go.

Fantastic, well done.

Now the sun, a candle and a mobile phone all produce and give out light, so they are light sources.

A metal spoon, however is shiny, but it doesn't produce its own light and it's the same with the moon.

So the moon appears to shine, but it doesn't actually produce its own light.

Some objects appear to shine, but they are reflecting light from a light source and we call these light reflectors.

So the tree bobble appears to shine, but light is being reflected from its surface.

And when light shines onto this jacket, it's also reflected from its surface.

Now light is also reflecting from the windows.

So true or false? All light comes from the sun.

Is that true or is that false? 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.

The answer is false.

Now let's justify our answer.

Is it because A, light only comes from natural sources or is it B, light can come from many different sources? 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 B, light can come from many different sources, not just natural ones can also come from manmade, or human made ones as well.

Why do some objects that do not produce light appear to shine? Is it because A, they're made of a transparent material? B, they are all made of metal.

C, they are reflecting light from another light source, or D, they are all objects that are that are lit by the sun.

So again, 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 come back when you are ready.

Off you go.

Fabulous, well done.

The answer is C.

They are reflecting light from another light source.

So here is your first task and it says, look at the objects provided for you.

So we have a mirror, electric candle, so it's battery powered.

We've got kitchen foil, a silver coin, a high-vis vest, and a torch which is switched on.

It says, discuss with a partner which ones you think are producing light and which of these are just reflecting light.

And explain why you think this is.

And explain why you think this is.

So I'll give you five seconds now to discuss with your partner.

However, if you and your partner need longer, that's absolutely fine.

Just pause the video here, come back when you are ready.

Off you go.

Fantastic, well done.

So Jun had a go at this question and he says, "I think that a mirror, an electric candle, a hi-vis vest and a torch are producing light because they give out light, And I think that the kitchen foil and a silver coin are reflecting light because they don't give out light." So I want you to just think about Jun's answer and we will come back to this.

So onto the next part of our learning, which is identifying light sources and reflectors.

Now Jun wants to identify and group the objects into light sources and light reflectors.

So what could he do to find out which objects belong to which group? Jun says, "I could direct light from a torch onto each object.

If the object shines, then I can identify it as a light source." What do you think about Jun's idea and why? So he's saying, again that he could direct light from a torch onto each object, and if it shines, then you can identify it as a light source.

So think about his statement.

I'll give you five seconds, but if you need longer, that's absolutely fine.

Just pause the video here and come back when you are ready.

Off you go.

Fantastic.

Well done.

So Jun has decided he's going to record his results in a table.

So he's got his shining, which is his light source.

So he thinks the mirror, the torch, the silver coin, the hi-vis vest, the kitchen foil and electric candle he's saying is all of the light sources that he's going to use.

Now Jun's results show that all the objects he tested in this way do appear to shine.

So that's all the objects that are in the table there.

Now can you spot anything wrong with what Jun has done? Have a really good look.

If you need to,you can pause the video here so you can have a really good look at this and see where he might have made a mistake.

Off you go.

Fantastic, well done.

So Aisha says that "Light sources shine because they produce light, however, light reflectors only appear to shine, but this is because they are reflecting light from a light source and shining a light onto the object is not a good way to identify and group them." Now, how would you test the objects in order to identify and group them as life sources and light reflectors? I'd like you to pause the video here and have a really good think.

Think about what Jun has done, and think about why he's done it the way he's done it and think about what Aisha is saying as well.

And then I want you to think about how you would go about testing these.

Pause the video here and have a go at that.

Off you go.

Fantastic, well done.

Now Aisha has an idea to help Jun, and she says, "You can take the objects into a very dark room and find out which objects you can see.

So all light sources are going to give out a light and light reflectors won't be seen because there is no light for them to reflect." Now what do you think about Aisha's idea? 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 is there any other suggestions that you might have apart from what Aisha has suggested? 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.

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

When we are thinking about whether or not objects produce light, what groups should we classify them into? Should we classify them into light producers and light consumers, lights and non-lights, or C, light sources and light reflectors? Have a really good think about this one.

I'll give you five seconds.

However, if you do need longer, just pause the video here, come back when you're ready.

Off you go.

Fantastic, well done.

The answer is C, we should be grouping them into light sources and light reflectors.

Now here we have Jacob, and Jacob grouped different objects as light sources and light reflectors.

Which object has he identified incorrectly? So let's take a look at the light source column.

He's got fire, the moon, lightning or television.

And in the right light reflector column, he's got saucepan, silver ring, water and window.

So which of those objects is in the wrong column? Is it A, the moon, B, water, or C, something else? I'll give you five seconds to think about your answer.

If you need longer, just pop the video on to pause and come back when you are ready.

Off you go.

Fantastic, well done.

The answer is A, the moon.

Now the reason why the moon is not a light source, and it is a light reflector is because it reflects the light from the sun, which is what makes it shine.

And it does appear as though it's a light source in the night sky, but that's actually incorrect.

It's just reflecting light from the sun.

Now it says to use Jun's objects from task A, and place each object one at a time into a box with a secure lid and look through a small hole in the side or the top of the box.

So here we have an example of that, we have a black box and it's got a small hole in the top, but there are no other holes in this box.

Now you're going to put the objects from Task A into the box and see if it's producing any light.

And you're going to use your observations to identify and group the objects into light sources and light reflectors.

So think really carefully here.

If the object is producing light, what do you think you're going to be able to see? Now if it is just reflecting the light, think about what you might see then.

And then you are going to use those to group the objects into the light sources and light reflectors.

So kind of using Aisha's example here of a dark place.

So I want you to pause the video here, and I want you to have a go at that activity and come back when you are ready.

Off you go.

Fantastic, well done.

Now once you've done this activity, and you've grouped those objects into light sources and light reflectors, you are going to describe to a partner why you've grouped them in this way.

So don't just talk about, these are the light sources, and these are light reflectors.

Really describe what you've done in this investigation, and what you saw when you peered in through that hole.

So I'd like you to pause the video again here, so that you can describe to your partner really clearly why you've grouped them in the way that you have.

Off you go.

Fantastic.

Well done.

So using your observations to identify and group the objects into light source, and light reflectors, your results may have looked like these.

So here on the left hand side we have the light source, which is the torch and the electric candle.

And that's because they give out light, they produce it.

Now the light reflector you will have seen was the mirror because that is reflecting the light.

The silver coin, you have a hi-vis vest in the light reflector section as well, and kitchen foil.

Now all of the objects in the light reflector section, they do appear to produce light.

However, that's only if there is a light source reflecting on these objects.

That's the only time that it appears to shine, and does appear almost as though it is a light source itself.

However, we need to be really careful about making those distinctions.

Now let's do a summary of your learning.

And it says light can come from many different sources such as the sun, stars, torches, lamps, and candles.

Some objects appear to shine, but they are reflecting light from a light source and objects can be identified and grouped as light sources and light reflectors.

Now again, like I said throughout the video, we need to be really careful with what we are identifying as a light source and what we're identifying as a light reflector.

And now we have that fantastic box that you have made where you can put objects into there just to be a 100% certain that you are correct about it.

Because we can see in this picture with the hi-vis jacket, it is so bright that it does appear to be producing its own light, but without the light source, the hi-vis jacket would not be visible to the eye.

Now you have worked so hard today, there's been lots of new learning, lots of new information for you to be taking in, and I am so proud of you.

You've used your critical thinking, and you have done a fantastic job.

So well done everyone.