Thursday, 28 May 2015

Enquiry into World Time Zones

How is life in the future Sydneysiders?!?

Day 1 of Our Enquiry into World Time Zones........

Lead In:

We started our enquiry into world time zones with this question. 

We had a moment to think about this by ourselves before doing a ‘talk and turn’ with someone beside us.  We then shared all the ideas we had.   Some of us were able to explain how Sydney is in a different time zone and so it is later there then it is here and therefore ‘it’s sort of like being in the future compared to our current time here in Switzerland.’   We debated whether or not it really is in the future with children being encouraged to support their theories with prior knowledge.

I asked if anyone has seen the fireworks displays happening around the world on TV on New Year’s Eve.  Quite a few had and could remember that we usually see the fireworks happening in Auckland or Sydney first.     But, why is that?     What are these time zones we keep mentioning and how do they work?

Who has experienced jet lag?   Why, do we think, our bodies get confused when we travel through different time zones?   We shared some interesting theories about why this happens.

The day before, I had secretly emailed our parents asking if they had relatives or family friends around the world who wouldn't mind us ringing (preferably via Facetime) them during maths.  I got a pretty good response.  

So, with our world map displayed I surprised some children by Facetiming a relative or family friend living in a different time zone to us. (Imagine how surprised you would be if Dad; Grandad or an Auntie suddenly has her face pop up in your maths class! The surprised expressions were brilliant! :)  ) 

With each new phone call we recorded on our world map, what the current time, date and season was.

° Facetime # 1:  A student’s dad was working in Jakarta, Indonesia.

   When we rang him, he told us the time was 14:10 on Thursday 28th May. When asked about what season it was there, he explained how Indonesia has two seasons - a dry and wet season.

° Facetime # 2:  A student’s best friend was in Lisbon, Portugal.

   He told us the time was 08:20 on Thursday 28th May. (One hour behind us here in Switzerland and of course, also spring)  Some of us found it interesting that Portugal is so close to Switzerland & yet it is in a different time zone!

° Facetime # 3: A student’s uncle was in Sydney, Australia.

   He told us the time was 15:45 on Thursday 28th May and it was autumn. What was extra lucky, was that James' uncle was a pilot for QANTAS.  We learnt how when he flies to South Africa from Sydney he is always chasing the Sun.  He mentioned crossing the International Dateline (The what?!?!) and how people tend to get worse jet lag travelling west.  Why is that?!?

° Facetime # 4: A student’s uncle was in Arizona, U.S.A.

    He told us the time was 23:50 On Wednesday 27th May.    (WAIT!!!  Yesterday?!?!?) And we found out it was almost summer and 75°.  75°?!?!?   Oh, yes! In Farenheit, not Celcius...... 

We then looked at our map and made some statements together about what it tells us about time zones. Some of which included:

   ° West is behind in time and east is ahead in time

   ° Even countries very close to us can be in a different time zone

   ° There must be a system to calculate the time differences - there are lines
      that mark a new time zone.

   ° It can be 'yesterday' in North & South America

   ° the Southern Hemisphere has the opposite seasons to the Northern

   ° Countries close to the Equator only have two seasons

To help them take ownership of their learning and for me to find out what each child actually knows about time zones already, we each began a KWL chart.   We filled in everything we already know about world time zones and then wrote some questions about things we wanted to learn.

This turned out to be a great pre-assessment.  I could see what students already knew about time zones and what directions they would like to lead their enquiries towards.

Some of our wonderings include:

Time Zone Wonderings:

° How did people divide the world into time zones?

° How many time zones are there?

° Why do we need time zones?

° Does the time zone change more the closer you get to the Equator?

° How can we use the time zone lines on a map to find out what time it is in other cities?

° How can it be a different day in other countries?

° Is it possible to have time difference inside 1 country?

° When travelling west in a plane, why doesn't the Sun ever set?

° Is there a zero time zone?

° What did people do before time zones were invented?

° If it is the same date in Australia as it is in Switzerland, how can it be a different season?

Jet Lag Wonderings: 

(I wasn't expecting so many wonderings about jet lag, but there was a strong interest in this and it does connect with the mathematics of time zones so why not?)

° Why doesn't our body do things to adapt naturally straight away when travelling?

° Why do we get worse jet lap when travelling west?  /  Is that the same for everyone?

° Do we get worse jet lag travelling from the Northern Hemisphere to the Southern Hemisphere across  many time zones? 

° Which is the worst flight people travel with for jet lag in the world?

With these great enquiry questions, we are ready to launch into some very interesting investigations........



 Day 2 of our enquiry.......

We discussed what we learnt yesterday about time zones.  The travelling west causing worse jet lag was a hot topic, so I asked what we could do to find out.  Someone suggested we could send a Google form survey to our parents to see if they also experience worse jet lag travelling west, so that's what we did.

Our Google form survey was:

Do you experience jet lag worse travelling east or west?

° travelling west?
° travelling east?
° I've not noticed a difference
° I've never experienced jet lag

We'll take a look at the results on Monday.

I then introduced two key concept lines of inquiry we would be exploring today since these two came up a lot in our KWL charts from yesterday. We would be exploring:

° FUNCTION: How time zones work

° CAUSATION: Why time zones were created this way

We began with causation:

How, do we think, were the time zones created?

It's important that children are given opportunities to formulate their own theories, so they spent a few minutes coming up with a theory and using a world map to help them record their ideas.

We shared our theories with our table partners.


We then investigated the maths behind time zones together based upon some theories shared.

We looked at a clay ball imagining it to be the Earth.  

We cut it in half 'along the Equator'.

The shape we find is a circle (well almost a circle as we know the Earth isn't an exact sphere)

What do we know about circles?

- They have 360°


- Because 36 has many factors so it was considered a good number to divide a circle into.  


What numbers can we evenly divide  360 by?

We used our calculators to find the factors.   Eventually someone shared how 24 and 15 are factors of 360.   

How is 24 connected to measuring time?

- Oh!  24 hours!!!!!  

So, if we know the Earth is divided into lines of longitude and we know a circle is 360°, what has someone done to create time zones?

- They divided the Earth into 24 time zones because there are 24 hours in 1 day!

- And there must be a connection with 15.......

- Maybe each time zone is 15° wide?

- Would that add up to 360° though?

We discussed this theory with our table partners and decided it seems logical.  A few of us still seemed a bit puzzled so we watched this YouTube: 

World Time Zones, GMT, Intern Dateline

What has this helped us to understand?   Let's take a look at this YouTube:


Our understandings were growing.......

We made some connections with Greenwich meridian -  where have we heard meridian before?

- a. m   and p.m,  the m is meridian in Latin.

And so we come across this word again in relation to time.

Greenwich Mean Time - where have we heard of 'mean' before?   

- Mean means the average

- So, is Greenwich Mean Time the average time zone for the world?

To help us visualise our new discoveries we cut up a world map into 24 'time zones' at along the 15° lines of longitude.

If it was midday in the Greenwich time zone, what would the time be in each time zone heading east? We relooked at our world map from yesterday. When we rang Jakarta and Sydney, were they ahead in time or behind?  What about when we rang Lisbon and Arizona?  So, the next time zone heading east would be how many hours ahead of GMT?

We recorded our ideas.

What about when we are heading west from Greenwich?


What happens when we get to the end of the map?

We rolled them into cylinders and shared our theories......

We get to the international date line!

What is that line about?

What happens when we cross it?

Which side should we be on and travel to if we want an extra long birthday?

If we flew from Manila to Los Angeles, would we gain or lose a day?

On our return flight, would we gain or lose a day? Why?

We then compared the map we made and discussed what we noticed about this time zone map with our table partner.

Some wonderings & discoveries I overheard which I brought up for the whole class to discuss.....

- Why is the UK and Portugal in a different time zone to the rest of Europe? 

- Wow! America has 6 time zones!!!

- Why does China only have 1 time zone when it is so large?

- Which country has the most time zones?

- Is Alaska in the same time zone as Hawaii? 

- Why is Bangladesh in its own time zone?

- But the UK looks like it is in the same time zone as France!

- There is one town in Greenland that is in a separate time zone! Why?

- If you are driving across Australia, do you have to change your watch?

To help us, we also discussed:

Would it be logical for a country the size of Switzerland to split into different time zones?

FUNCTION: How we can calculate the time in different time zones

To investigate how we can find out the time of cities in different time zones, we began more easily with Greenwich being midday.  We each chose cities around the world and worked out what time it would be there. 

We then chose a different time for Greenwich and did the same for other cities.

Now that we have a pretty good understanding, our next session will be exploring some of our questions we have on our KWL charts......

(These enquiries will be updated soon.........)

Day 3 of our Time Zone Enquiries.........

Lead In /Review: 

What does this image tell us about ways we measure time?

We discussed what we had learnt and knew about time zones and reasons we might see clocks like these displayed together.  How might it help guests at a hotel to have these clocks at the reception?   Where else have we seen world time clocks displayed?

So, why do we need to learn about world time zones? How can knowing this help us in our lives?

We then watched this 4 min youtube to help us reinforce visually what we've learnt about how the time zones were created.

What did it help us to understand a bit better?

The YouTube helped us to also find out why Greenwich was chosen as 'time zero'.

One student thought it was interesting that even though it was a Canadian who came up with the idea of a universal world time zone system, even he chose Greenwich London.  

Why is that?

Why was London so important?

We were also blown away that the time zone system was only invented 85 years ago!!!  What were people doing before then?!?!?

Another student then shared a fascinating idea:

- So, if the world was flat, we wouldn't need time zones? Do we only need them because the Earth is a sphere?

This stirred an interesting debate and so we used a torch to see what it might look like if the Sun passed over a flat Earth:

- But wouldn't it be too hot?

- Would the whole Earth be like the Equator?

- Wouldn't the Arctic and Antarctic ice melt?

- It would make life easier for everyone though. We would all have the same time!

- But the Northern Hemisphere would still have a different time to the Southern because the Sun is passing down!

Then someone else posed an interesting question:

What time zone are you in if you are standing directly on a time zone line?

- You are in both at the same time.

- But how can that be?  What if you need to tell someone what time it is where you are?

- Maybe it depends on what time zone you have just come from.  If you are walking from time zone A, the moment you stand on the time zone line you should still say you are in the time zone you came from. The moment you step over the line you have then changed time zones.

Kids problem solving their own problems.  Does it get better than that?

We had a choice of levels for our activity in learning how to calculate the time in different cities (see pic)

Most paired up to start at level 3 and a few felt they could confidently give level 4 a try.  A few of us felt we would be better at trying level 1 or 2.  

(The kids in my class are so used to evaluating where their skills are at that they always choose levels that will challenge their thinking just enough.)

We made little people out of blutac and placed them in different time zones.

We then 'made phonecalls' to where the other blutac person was in the world and asked what the time was there.

Their confidence in calculating the time in different cities grew and the children began challenging each other more and more.  Those doing the most challenging level needed some time to start seeing patterns or creating strategies to see where in the world would be early a.m.  They all got there though and excitedly shared their strategies with other groups trying to work it out.  Their 'phone calls' of waking someone up were hilarious!  Maths learning should always have some laughter involved.....:)

Before heading out, we looked at our Google form survey results we had sent to our parents.

It seemed there wasn't really a big distinction between experiencing worse jet lag by travelling east or west.

One of our parents, after doing the survey, emailed us some really interesting information regarding jet lag.   

We read through her email and chatted about how and why jet lag can affect us all differently.

So great when we can bring parents' knowledge into our classroom! :)

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