Lesson video

Hello.

My name is Mrs. Gulliver, and I am so happy that you are joining me for this geography lesson today.

Our lesson today is called longitude and time zones, and it's from our unit on time zones: can we time travel on planet Earth? By the end of today's lesson, you will be able to identify the Prime Meridian and understand time zones.

Some of this learning might be a bit new for you today, but that's okay.

I'm gonna be here the whole lesson to help you through.

We've got three key words for our lesson today, so I will say them and then I will give you a turn to also practise saying them.

So the first one, Co-ordinated Universal Time.

Well done.

That's a bit of a mouthful, isn't it? Next one, Greenwich Mean Time.

Well done.

And the last one, Prime Meridian.

Great.

We're gonna be finding out about these during the lesson, but let's just go through their meanings quickly.

So Co-ordinated Universal Time is a standard system that is used to set all the world's time zones.

Greenwich Mean Time is the time at the zero degree line of longitude, which is also known as the Prime Meridian.

And the Prime Meridian is the line of longitude at naught degrees from which the other lines of longitude are measured east and west.

Our lesson's going to be broken into two parts today, so our first section of learning is going to be about how were time zones created.

Now, in our last lesson, we learned that the sun's rays always travels in straight lines and the side of the earth that is facing the sun is experiencing daylight, while the other half that's facing away from the sun is in darkness and that would be nighttime.

So daylight happens when places face towards the sun.

Planet Earth is constantly rotating and spinning on its axis, and it makes one full rotation every 24 hours.

This means that as the planet spins, the side of the Earth facing the sun changes and places across the globe experience midday, the middle of their day, at different times.

Places around the world are experiencing nighttime at different times as they rotate around the Earth and come into and out of that sunlight.

Now, because not everyone is experiencing daylight at the same time, this can cause some problems. I've got Izzy here and she says, "It is lunchtime in the United Kingdom.

I want to call my granny who lives in New Zealand," but her mum said not to.

Hmm.

New Zealand is on the other side of the globe to the UK.

Can you think why mum might have told Izzy not to call Granny at lunchtime in the United Kingdom? Have a think with the person next to you.

Well done.

If New Zealand is on the other side of the globe to the UK, which it is, when it is lunchtime in the United Kingdom, it will be the middle of the night in New Zealand and I'm not sure that Granny will still be awake to take Izzy's call.

Let's see if we can help Izzy work out through the rest of this lesson.

When would be a good time for her to call Granny? Now, to help Izzy, we need to think back to what we learned last time about lines of longitude.

And we know that lines of longitude are imaginary lines that run from the North Pole to the South Pole and are all the same length.

We know that they can give our position in degrees east or west of the Prime Meridian line, which is shown here in red, and that is located at naught degrees longitude.

And we found out that places along the same line of longitude or meridian all face the sun at the same time, so these are all in the same time zones.

And I'm sure you remember that the Prime Meridian runs through Greenwich in London.

Now, Greenwich Mean Time is the average time when the sun crosses the Prime Meridian at Greenwich in London, and GMT, Greenwich Mean Time, was created in 1884 and was used to help sailors find their position in longitude when out to sea.

And there's that Prime Meridian shown to us in that red line running through Greenwich and London in England.

However, we want to know how to calculate the time in other places.

Now, one full rotation of the Earth takes 24 hours and passes through 360 degrees, so I wonder if we could work out how much the Earth rotates in one hour.

What calculation would we need to do to find out how many degrees the Earth rotates in one hour? Well done.

We would have to divide the 360 degrees into those 24 hours.

We'd have to do 360 divided by 24.

I wonder if any of you could solve that.

Great job.

If we split those 360 degrees into 24, we would work out that the Earth rotates 15 degrees each hour and we can use this to help us calculate our time zone.

So now that we know that Earth rotates 15 degrees each hour, this information is used to divide the globe into zones of time, time zones.

And time zones are measured from the Prime Meridian at naught degrees longitude, where the time is set to Co-ordinated Universal Time.

So at the Prime Meridian, everyone is on what we call UTC and we measure the time around the world either west or east of that time zone line, that meridian, longitude line.

So the Earth is divided into 24 standard meridians, or lines of longitude, at intervals of 15 degrees because we worked out that was how far the Earth rotates in one hour.

And you can see here, there's the Prime Meridian line at naught degrees longitude running through Greenwich and that as we move east, the time zones are moving up one hour per time zone.

So the blue time zone first to the east of the Prime Meridian is +1 hour and the next, the brown one is +2 hours, the blue one, +3, the brown one, +4, like it's the same as we move west.

But apart from being plus one hour, we are taking away one hour.

So the first blue time zone west of the Prime Meridian would be -1 hour.

The next one is the brown one which would be -2 hours and then it goes back to the blue time zone which would be -3 hours and so on.

So these lines, all of these lines are the basis for marking the boundaries of 24 time zones all around the world.

And I'm sure this information is going to help Izzy work out when she should be calling her grandma.

I've got a check for you.

True or false? There are 24 time zones on Earth.

(sneezes) Excuse me.

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

Well done.

That's true.

Now, have a look at these statements to see which one you should choose to justify your answer.

a, the Earth takes 24 hours to rotate 15 degrees, or b, the Earth takes one hour to rotate 15 degrees.

Pause the video and have a think.

Great job.

We worked out, didn't we? That the Earth takes 1 hour to rotate 15 degrees.

So as we mentioned, times in countries to the east of the Prime Meridian is always ahead of that in the UK.

We add on extra time, it's ahead of time to the UK.

And you can see that that blue time zone there, that is three time zones east of the Prime Meridian, is three hours ahead of time in the United Kingdom at the Prime Meridian.

So any places located along the Prime Meridian would be three hours behind the time in the blue time zone located.

That is three hours ahead of time at the Prime Meridian.

And the same goes but travelling west, opposite.

So time in countries to the west of the Prime Meridian is always behind that of the UK.

And we've got our minus signs in front of the times at the top and bottom of the time zones and the minus signs means that we have to take away time, it's behind that of the UK.

And you can see that the blue time zone located three jumps west of the Prime Meridian there would be three hours behind the time in the United Kingdom.

So if it was four o'clock in the afternoon in the United Kingdom, what time would it be in that blue time zone if it's three hours behind? Well done.

It would be one o'clock in the afternoon for countries in that blue time zone.

I've got another check.

Time in countries to the west of the Prime Meridian is always, a, behind the UK, b, the same as the UK, or c, in front of the UK.

Pause the video and have a think.

Well done.

Time in countries to the west of the Prime Meridian is always behind the UK.

Here's our first task of the day.

I would like you to use an atlas and in that atlas, I would like you to choose one time zone and record whether it is plus, east, or minus, west, of the Prime Meridian.

Then for that one time zone, we would like you to locate cities found within that time zone and record them in the country they are in.

So you would need to tell me if you are plus or minus from the Prime Meridian, depending on if you are east or west, and then go all the way down that time zone to locate a range of cities and also note down what country those cities are found in.

Pause the video now and have a go at your task.

Good luck.

Here's my example for what I did to solve this task.

So I looked at the time zone that is -4 hours from the Prime Meridian.

So it is west of the Prime Meridian and it's four hours behind time at the Prime Meridian.

And here's some of the cities and countries that I found.

I found Atlanta in the United States of America, Toronto in Canada, Kingston in Jamaica, and Lima in Peru.

I wonder if you looked at the same time zone or maybe you looked at a different one.

Now, we've looked at how time zones were created, we can look at different time zones around the world.

So let's get going with our second part of lessons, how we can investigate time zones.

So as we found out, time zones can help us to work out the time in different places across the world.

Do you remember Izzy from the start of our lesson? Izzy wanted to call her granny at lunchtime, at midday in the United Kingdom but her mum told her not to.

Izzy now realises that time zones can help her work out when the best time would be to call her.

And do you remember her grandma was in New Zealand? And here's New Zealand shown on this world map.

And Izzy has realised that New Zealand is in the +12 hour time zone.

And this means Granny is 12 hours ahead of Izzy.

So New Zealand is as far away as it possibly could be from the United Kingdom.

You now work out when would be a good time for Izzy to call Granny.

Have a think with the person next to you.

I wonder what times you came up with.

Izzy said, "If I called her at seven o'clock in the morning UTC, then it would be seven o'clock at night for Granny.

We would both be awake and we were both be in daylight." Great idea, Izzy.

A much better idea than calling her at midday UTC.

So we can see why time zones are so important for people who need to communicate across the world and live in different time zones.

Now, without using a time zone map, it can be tricky to work out the time in other countries around the world.

But there are ways that we can see what's happening in other countries and webcams are a really useful source of information about what is happening in places which are in different time zones.

They are live cameras which are recording exactly what's happened in a certain place.

Lots of cities have live stream videos that you can view on the internet and you can tell by watching these videos what time of day it is, what sorts of things people are doing, what the weather may be like, so they're a great source of information for us.

So these webcams show you exactly what's happening at a current time at the same time in a different geographic location.

And can you see here, I've got an image from a webcam of New York City.

What sorts of information can you get from this image of New York City? What sort of time of day do you think it is, what do you think the weather's like, have a think with the person next to you.

Well, if we think about the daylight, first of all, it is still daylight but some cars have got their headlights on.

So maybe it's coming towards the end of the day and starting to be dusk, so maybe they're starting to go into nighttime.

Or maybe it's very early in the morning and the sun is just coming up.

Maybe it's dawn.

Hmm, I can see it also looks like it's raining, so that may be why they've got their headlights on 'cause sometimes when it's raining, it's a bit darker, isn't it? And I can see that people are walking up and down the streets.

They might be going to work or they might be going shopping.

So it can give us lots of information from looking at webcam images.

Webcams often also usually have a time stamp on them so that you can tell what the local time is.

Now, Lucas has used webcams to look at lots of different cities across the globe, and it was 12 midday UTC in England when he took the following screenshots from three different webcams around the world.

Lucas was just about to go for his lunch when he looked at these webcams. So let's see what people around the world were doing at the same time when Lucas was about to go for his lunch.

So this was the first image that Lucas took.

What sort of time of day do you think it is? You could have a look at the timestamp and the image to give you some information.

Well done.

It's five o'clock in the morning, so we can see that the sun's just beginning to come up.

The street lights are still on, so it's not very light.

So this webcam is from Mexico City, and Lucas says, "Mexico City is seven hours behind UT," so if it's midday in London, it's five o'clock in the morning in Mexico City.

And Lucas says, "I can just see the sun is rising and there are no people on the streets." They're probably all still in bed sleeping, aren't they? The next webcam that Lucas looked at was in Rome in Italy and you can see when it's midday, 12 o'clock UTC in England, it's two o'clock in the afternoon in Rome.

And it looks slightly different, doesn't it? Well, quite different to Mexico City.

So it's two o'clock in the afternoon in Rome and there are lots of people walking around the city, it's very busy, and it looks like it's a cloudy sunny type of afternoon.

Maybe people have just finished their lunch, maybe they're having a look at some of the sites in Rome.

And the final place that Lucas took a snapshot of a webcam at was Tokyo.

So it's midday in London, and at Tokyo, it was nine o'clock in the evening and you can see that the sun has set, that Tokyo would now not be facing the sun.

Lucas says, "This webcam shows Tokyo, Japan which is nine hours ahead of UTC.

It's nighttime because the sun is set but the city still looks quite busy," thus you can see lots of lights on in buildings, can't you? And on the roads, it looks like there's lots of transport still happening.

So one time in England, all sorts of different times will be happening around the world and Lucas looked at three different places which have got times, one of them had times behind the time in London and two of them had times ahead of the time in London.

I've got a check for you.

If the UTC was 12 noon, so midday, which time zone do you think this webcam could be from? Is it one hour ahead of UTC, three hours ahead of UTC, or eight hours ahead of UTC? And we're thinking about it being ahead of 12 noon.

Pause the video now and have a think.

Well done.

It would've been eight hours ahead of UTC.

It looks like the sun's just setting, doesn't it? So it's probably about 8:00 PM at night.

Now your final task for the day, I would like you to use some webcams on the internet to explore different time zones around the world.

I'd like you to complete the table below.

I'd like you to do your location, which is UTC, and fill in your current time.

And rather than webcam information, you might tell me what's happening if you look out the window where you are right now.

Then, you're going to find at least three different locations like Lucas did, write down what time zone they are in, if they are plus, so ahead of UTC, or minus, behind UTC time, what the time is in that location, and what you can work out from the webcam.

Have an investigate now some different places around the world.

Pause the video and I'll see you soon.

Which locations did you investigate? I bet it was fun looking at different places around the world.

I looked at three different locations.

I said, my location is in Greenwich, United Kingdom, it's UTC, and it's 10 o'clock in the morning.

It's the middle of the morning and I'm at school.

I then looked at somewhere on the same line of longitude, in the same time zone, and I got to Accra, Ghana, which is also UTC and 10 o'clock in the morning and it's exactly the same time as my location.

And when I looked at that webcam, there were lots of people and cars on the street, so it's seem mid-morning.

I then went right to the furthest time zone that I could and I went to New Zealand, where Izzy's grandma lives.

And I looked at the city of Wellington which is 12 hours ahead of time where I am in Greenwich.

And it's 10 o'clock at night in New Zealand.

It's dark but there are some cars with lights on driving in the city.

And then I also looked the other way.

I went to time behind UTC and I got to New York and New York is in a time zone that is five hours behind where we are in London.

And so at 10 o'clock in the morning, for us, it's 5 o'clock in the morning for New York.

And it said, when I looked at the webcam, I thought the sun is just about to rise in New York.

Some people are waking up and have got their lights on.

I hope you enjoyed investigating those different places as much as I did.

Let's summarise our learning for today, then.

Time zones are measured from the Prime Meridian at naught degrees longitude, where the time is Universal Co-ordinated Time, UTC.

Earth is divided into 24 standard meridians at intervals of 15 degrees, which are the basis for delineating 24 time zones, for marking those 24 different time zones.

Time zones to the east of the Prime Meridian are UTC, or GMT, plus, and time zones to the west are minus UTC, GMT.

And we also found out that webcams are a useful source of information about what is happening in places which are in different time zones.

Thank you so much for joining me for this lesson on longitude and time zones.

I hope you've enjoyed it as much as I have.

I hope to see you soon.

Bye.