Lesson video

Hello, my name is Mrs. Gulliver and I'm so happy that you are joining me today for this geography lesson.

Our lesson today is called Day and night, and it's from our unit on time zones: can we time travel on planet Earth? Today, by the end of the lesson, you will be able to explain why we have day and night and what lines of longitude are.

We've got five keywords for our learning today.

So I will say them and then I will give you a chance to say them.

So our first one, globe.

Your turn.

Well done.

Rotation.

Great.

Longitude.

Well done.

Latitude.

Great.

And our last one, axis.

Brilliant.

We'll learn about these words today, but let's just go through their meanings.

So a globe is a map of Earth on a sphere.

A rotation is a complete circular movement of an object around a fixed point or an axis.

Lines of longitude are imaginary lines on Earth showing position east or west of the prime meridian, measured in degrees.

Lines of latitude are imaginary lines on Earth showing position north or south of the Equator, also measured in degrees.

And an axis is an imaginary straight line through Earth, which rotates around it.

Our lesson's split into two parts today.

And the first part of our learning is going to be about why do we have day and night? As you know, planet Earth experiences periods of night and day.

I've got a friend who's helping me today and they say that they know that daytime is when the sun shines and nighttime is when it's dark.

But why do we have these periods of day and night? Have a think with the person next to you.

As you know, Earth is a giant sphere like this globe, and you might have some globes in your classroom.

And the Earth is constantly rotating.

It's constantly spinning around on its axis and it makes one full rotation, one full turn all the way around, every 24 hours.

And we call each complete rotation one day, a day.

We're going to watch a quick video of the Earth rotating on its axis as it's seen from space.

So we're imagining we're zooming off of planet Earth into space and looking back at Earth to see how it rotates.

Although this video has been sped up so we can see the rotation happening, if we watched it in real time, it would look much slower than this.

But this is what it would look like if we were in space looking back at Earth.

Of course, there's another important body in space that also gives us night and day, and that's the sun.

So the sun, with the rotation of Earth, is what causes night and day.

The sun gives us heat and light, and at any moment, half of the Earth faces the sun and experiences the light and the heat from the sun's rays while the other half is in darkness.

And the half that is facing the sun is in daytime and the half that is facing away from the sun and is in darkness would be experiencing nighttime.

When the UK turns towards the sun, it is morning, and as the Earth continues to rotate, the sun appears to rise above the horizon, and at midday, the sun is at its highest point in the sky.

We'll have a little look to see what this looks like.

When the UK turns towards the sun, it is morning.

We move from darkness to light.

As the Earth continues to rotate, the sun appears to rise above the horizon, and at midday, the middle of the day, the sun is at its highest point in the sky.

As the planet rotates, we move away from the sun and into darkness.

We would now be on the side of Earth facing away from the sun, and the UK stays in darkness until the Earth rotates back round to face the sun.

Let's have a look at what it looks like.

So as you noticed, it gets darker in the evening as the UK rotates away from the sun.

And you could try this out in your classroom using a globe and a torch.

On your globe, find where the United Kingdom is and you could put a pin or some Blu Tack on this spot to help you locate it.

Then shine the torch at the globe from a fixed position, hold it in place, and the torch is pretending to be the sunlight.

Slowly rotate the globe and see what happens to the United Kingdom as it travels through one day, one complete rotation.

So go in your class.

Now, if we imagine we zoomed away from the planet again and went out into space above the North Pole, we would look back on the Earth and we would see that it is rotating in an anticlockwise direction, the opposite direction to the hands of a clock.

And because of this rotation, we see the sun rising in the east and setting in the west every day.

I've got a check for you.

True or false, when viewed from the North Pole, the Earth rotates anti-clockwise.

Is that true or false? Stop the video now and have a think.

Well done.

That's true.

And which of these statements would you use to justify your answer? Would you use A, the sun rises in the west and sets in the east, or B, the sun rises in the east and sets in the west? Pause the video now and have a think.

Well done.

I'm sure that you also thought that it was B.

The sun rises in the east and sets in the west.

Now, for your first task today, I would like you to complete the following passage about why we have night and day.

And you can see at the bottom there you've got some purple words to choose from to fill in each of the blanks.

I'll read the passage to you and then you can pause the video and see which word you think fits into which section.

Earth is constantly rotating on its, making one full rotation every, hours.

We call each complete rotation a.

This rotation gives us night and day.

At any moment, half of Earth faces the sun and experiences the light and heat from the sun's rays while the other half is in.

When viewed from the North Pole, the Earth rotates.

Because of this rotation, we see the sun rising every day in the and setting in the.

Pause the video now and fill in those blanks.

I'm sure you tried really hard with this task.

Let's have a look at the answers.

So Earth is constantly rotating on its axis, making one full rotation every 24 hours.

We call each complete rotation a day.

This rotation gives us night and day.

At any moment, half of Earth faces the sun and experiences the light and heat from the sun's rays while the other half is in darkness.

Well done.

When viewed from the North Pole, the Earth rotates anti-clockwise.

Because of this rotation, we see the sun rising every day in the east, well done, and setting in the west.

Great job with that first task.

Our second part of the lesson today is about what are lines of longitude? Well, lines of latitude and longitude are imaginary lines on Earth.

We can't actually see them on the planet.

Lines of latitude run around the world sideways and include the Equator, and these aren't actually related to time zones, but we're going to find out about the lines of latitude first.

You can see some of the key lines of latitude highlighted on that map.

We've got the Equator, the Tropic of Cancer and Tropic of Capricorn, and then we've got the Arctic Circle and Antarctic Circle.

These are some of the key lines of latitude and they all run parallel around the world.

They do not get closer together or further apart.

Now, the lines of longitude are helpful for us in telling the time, and these are all equal in length.

They run from the North to the South Pole, dividing the planet into segments, a little bit like the segments of an orange.

Lines of longitude are also called meridians, and you can see there's one highlighted in red there, and that's a very important line of longitude or meridian.

I'd like you to complete this check.

I'd like you to name the lines shown on each diagram.

So I'd like you to work out which diagram shows the lines of latitude and which diagram shows the lines of longitude.

Pause the video now and have a think.

Well done.

That first image shows us lines of latitude, we've got the Equator there in the middle.

and then the diagram on the right, that shows us the lines of longitude.

Great job.

Now, the lines of longitude are measured in degrees, just like a circle has 360 degrees in total.

And the Earth takes 24 hours to pass through 360 degrees.

One full rotation of 360 degrees of the Earth takes 24 hours, one day.

Longitude is measured from nought degrees at a special line, that line in red that was shown earlier, and this special line of longitude is called the prime meridian.

Lines of longitude help to give our position in degrees.

They give our position east or west of the prime meridian, and you can see the prime meridian there running through the United Kingdom.

Runs through lots of other countries as well and oceans and seas.

And you can see that the line west of the prime meridian is labelled 10 degrees W, 10 degrees west.

And the first line east of the prime meridian is labelled 10E, 10 east of the prime meridian.

So all of those lines are measured in distance in degrees from how far they are from the prime meridian line.

Each line of longitude or meridian runs through locations that will pass in front of the sun at the same time.

So all of the places on the red line of longitude, prime meridian line, will share the same time.

They will all be in the same time zone.

Prime meridian, the line at nought degrees longitude, runs through London and actually runs through Greenwich.

Now, this north-south line that marks nought degrees longitude passes through Greenwich, England, and this is called called the Greenwich or prime meridian.

Greenwich was chosen for the prime meridian because when the system of latitude and longitude was established, Great Britain was a world leader in exploration and Mapmaking.

Greenwich was the home of Britain's Royal Observatory, so they began measuring degrees from this line of longitude and gave it a special name, the prime meridian.

Now, I wonder, do you know where your school is on the map of the United Kingdom? Are you close to the prime meridian? Are you to the east of the prime meridian or the west of the prime meridian? On the opposite side of the Earth to the prime meridian, at 180 degrees, is the antimeridian.

The middle of the Pacific Ocean is where the east and west lines of longitude converge or meet 180 degrees and it's directly opposite the prime meridian line.

Got another check for you.

Lines of longitude are measured in degrees from, A, the antimeridian, B, the Equator, or C, the prime meridian? Stop the video now and have a think.

Well done.

That was C.

I've got your final task for you today.

I'd like you to use an atlas or a digital map to list all the countries that are located along the prime meridian.

So we know that the United Kingdom is located along the prime meridian.

Which other countries also are located along that line of longitude? Have a go, pause the video, and we'll come back together soon to see how you got on.

I'm sure you had a great go at that task.

It's brilliant fun looking at maps to see all of the countries located on the prime meridian.

And I know you would've found the United Kingdom.

If you were being really specific, you might have said only England.

France is also located on the prime meridian, as is Spain, Algeria, Mali, Burkina Faso, Togo, Ghana, and it also passes through Antarctica before reaching the South Pole.

Well done if you also located all of those countries.

Great job.

So just to summarise our learning for today, day and night result from Earth's rotation in relation to the sun, which appears to rise in the east and set in the west.

Lines of longitude are all the same length and give our position in degrees east or west of the prime Meridian.

The prime meridian, nought degrees longitude, runs through London.

The antimeridian, 180 degrees longitude, runs through the Pacific Ocean.

Thank you so much for joining me for this geography lesson on day and night today.

I hope to see you again soon.