Lesson video

Hi there.

My name is Mr. Tilstone.

I'm a teacher and I just love maths.

So, it's a real pleasure and a real delight to be with you today, teaching you a lesson all about time.

Today's lesson particularly, we'll be looking at problem solving to do with time.

So, it's a chance to bring all of those wonderful skills together.

So if you are ready, I'm ready, let's begin.

The outcome of today's lesson is, I can solve problems involving writing, telling and converting the time.

So, you've hopefully had some recent experience of time conversions.

We're going to put that into practise today.

Our keywords are my turn, interval, your turn.

My turn, convert, your turn.

Those words aren't too common, so let's have a look what they mean.

An interval is what is in between two values or points such as what's between nine o'clock and 9:30, for example.

And when we change a value from one form to another, we convert it.

Our lesson today is split into two cycles.

The first will be calculating time intervals, and the second using conversions to solve problems. So if you are ready, let's have a look at calculating time intervals.

In this lesson, you're going to meet Andeep, Izzy, Sophia, John and Jacob.

Have you met them before? They're here today to give us a helping hand.

So an interval is the amount of time that passes between a start time and a finish time.

Let's look at an example.

This is half past eight.

You might see it as 8:30 8:30 pm in this case you might see it as 20:30 using the 24-hour clock.

And let's have a look at this one.

So the analogue time will be nine o'clock, the 12-hour digital time, 9:00 pm, and the 24-hour digital time, 21:00 hours.

So this is how much time has passed in between the start time and the finish time.

How long is it? How much time is that? Well, that's a 30-minute or a half hour interval.

Can you see half an hour there? So that's what we mean by intervals.

And let's look at a different one.

So let's think about this.

What is that as an analogue time? What is it as a 12-hour digital time, and what is it as a 24-hour digital time? Well, that's quarter past six or 6:15 am, in this case, or 6:15.

And then this is the finish time.

So this is seven o'clock or 7:00 am or 07:00 hours.

And that's the amount of time that's passed, that's the interval.

That's a 45-minute or three quarters of an hour interval.

This is Pedro the panda.

Have you met Pedro before? You might have done.

Pedro started eating a watermelon at, hmm.

Can you see a time there? What time did he start eating that watermelon? It took him, hmm? What time did he finish? Well, let's investigate.

So he started eating a watermelon at 25 minutes past nine.

That's the analogue time, but it's going to be helpful today if we can turn that into a digital time.

So let's do that.

So instead of 25 minutes past nine, we could say 9:25, and it took him, let's find out, quarter of an hour.

Now again, it's going to be helpful if you can do a little conversion here.

Turn quarter of an hour into a number of minutes.

So how many minutes in quarter of an hour.

You might know this off by heart.

That's 15 minutes.

What time did it finish? Now, that's given us some numbers to work with.

So here we go.

That's the difference between the start time and the finish time.

So that's the interval.

So that 25 minutes, 'cause it was 25 minutes past at the start, plus 15 minutes, that's how long it took him, equals 40 minutes.

So it finished at 9:40, 40 minutes past nine, or you might call that 20 minutes to 10, both are correct.

And here we go.

Pedro finished climbing rocks at, hmm.

That's the time.

Have a look at the time.

What time did he finish climbing the rocks? And it took him, hmm.

What time did he start? We've got a slightly different type of problem here.

We know the finish time this time.

We need the start time.

So he finished climbing the rocks at 20 minutes to 10.

But it's going to be easy if we think of that as 9:40.

So that's what it's the digital time helps.

It took him, let's find out, half an hour.

It's going to be helpful if you can turn half an hour into minutes.

How many minutes in? Half an hour? 30.

So it took him 30 minutes.

What time did he start? So now we've got some numbers to work with.

So there we go, that's how long it took him.

So we can do 40 minutes, 'cause it was 40 minutes past, take away 30 minutes, 'cause that's how long it took him, and that equals 10 minutes.

So he started at 9:10 or 10 minutes past nine.

And there's that time.

Let's have a check.

Pedro started walking to school at this time in the morning.

So, what is that time? You might be able to do it in analogue time, that's good, but can you also turn it into digital time? That would be helpful.

So that's what time he started walking, and it took him quarter of an hour.

Can you turn that into minutes? What time did he get there? Pause the video, and give that a go.

Well, let's have a look.

So he started walking at 40 minutes past eight.

So we can use the number 40 plus 15, because that's quarter of an hour.

So 40 plus 15 equals 55.

So he got there at 8:55 or 8:55 am, or even five minutes to nine.

They're all acceptable answers.

Well done if you got that.

Pedro started searching for bamboo 'cause he loves bamboo at, hmm.

Can you see the time on there? What would you call that in digital time preferably? And finished at, hmm.

What would you call that in digital time? How long did it take? So we need to try and work out that interval.

So we started searching at 6:15.

So let's skip straight to the digital time.

Let's not even think about the analogue time.

6:15, and he finished at, what is that in digital time? 6:50.

How long did it take? So we've got some numbers to work within that 15 and that 50, that's the interval.

You might even be able to see without doing the calculation what that interval is.

It's a little bit more than half an hour I can see.

But let's work it out.

Could use a number line, start at 6:15, end at 6:50, and count on.

From 6:15 to 6:20, that's five minutes, and from 6:20 to 6:50, that's 30 minutes.

Add them together and you've got 35 minutes.

Pedro started walking at 16:15 and finished at 16:55.

How long did he take? Pause the video and have a look at.

Well, we've got some numbers to work with there, haven't we? We've got 15 and 55, so we could count on from 15 to get to 55, that would be the interval.

And it's 40 minutes.

So well done, if you've got 40 minutes.

It's time for some practise, I think.

So number one, A, Pedro started painting a picture at this time, and it took him half an hour.

Hmm, half an hour.

Can you turn that into minutes? What time did he finish? B, Pedro started playing football at this time, and it took him three quarters of an hour.

Hmm, think about what quarter an hour is, what is three quarters of an hour? You might have that fact already memorised.

What time did he finish? And number two, A, Pedro started his homework at quarter past five, and it took him 35 minutes.

What time did he finish? B, Pedro started reading a book at quarter past 10.

Hmm, turn that into digital time, and finished at 10 minutes to 11.

How long did he take? And C, Pedro started playing a game at five minutes past one and finished at quarter to two.

How long did he take? And again, my top tip, turn those into digital times, and then it makes it much easier to calculate.

Pause the video, good luck with that, and I'll see you soon for some feedback.

Welcome back, how did you get on? Well one, A, he started painting a picture at this time and it took him half an hour.

What time did it finish? Well, that's showing 11:10.

So 10 plus 30, which is half an hour, equals 40.

So he could say 11:40.

He could also say 20 minutes to 12, that's fine, they're both acceptable.

And then B, he started playing football at this time, and it took him three-quarters of an hour, that's 45 minutes.

So we can think of that as 4:05.

So that gives us a number five, five plus 45 equals 50.

So you can say 4:50 or 10 minutes to five.

Now you might have given the time in different formats such as am or pm, 12-hour time, 24 hour time.

There's some different possibilities there.

And you might have given those different possibilities for these questions too.

So Pedro started his homework at quarter past five, and it took him 35 minutes.

What time did he finish? Well, 15 because it's quarter past.

So 15 minutes past, plus 35 equals 50.

So we can say 5:50 or 10 minutes to six.

He started reading a book at quarter past 10.

So we could think that's 10:15, and finish at 10 minutes to 11.

So if we think of that as 10:50, that will be helpful.

So the interval between 10:15 and 10:50 is 35 minutes.

You might have used counting on strategy to go from 15 to 50.

And C, Pedro started playing a game at five minutes past one, so 1:05, and finished at quarter to two.

So I would think of that as 1:45.

How long did he take? So the interval between 1:05 and 1:45 is 40 minutes, and I think that became quite easy when we expressed it as a digital time.

Well, you're doing really, really well.

So let's move on to cycle two, and that's using those conversions to solve problems. Sophia is challenging John to see if he can recall different unit conversions.

Join in with them.

Okay, so a little bit of a quiz for you here.

So Sophia says, "How many minutes in an hour," right? If you know that, shout it out now.

Let's see what John says.

"60 minutes," he's right.

Did you say 60 minutes? Well done if you did.

Let's do another one.

"Months in a year?" Shout out if you know it.

John says, "12 months," and he's right.

Did you say 12 months? Well done if you did.

Let's do another one.

"Days in a week?" Shout it.

John says, "Seven days," and he is correct.

Did you say seven days? Well done if you did.

"Seconds in a minute?" Shout it out.

"60 seconds," says John, and he is right.

Did you say 60 seconds? If you knew all of those facts off by heart, and they came to you straight away, you're going to be able to use that in today's lesson.

It will make it easier.

So Sophia and John, just like you, can use these unit conversions when solving problems. Sophia is playing her favourite video game, and it's called Space Heroes.

Do you like playing video games? Sophia loves it.

Her mom has set parental controls allowing her to play for 100 minutes each day, and after that, the console switches off.

Maybe you've got parental controls on your console.

She starts playing at 17:00 hours.

What time will the console switch off? We can convert the minutes to hours.

So 100 minutes is one hour and 40 minutes.

Now that makes it a bit easier to work with, doesn't it? 17:00 plus one hour and 40 minutes is our calculation.

So 17:00 plus one hour is 18:00, and 18:00 plus 40 minutes is 18:40.

So that's what time? You might have called it 20 minutes or seven as well, that's fine, but 18:40.

It is Sports Day at Oak Academy.

Sophia, Andeep, Izzy, Jacob, and John, are running a timed race and here are their times in seconds.

So Sophia got 100 seconds, Andeep got 96 seconds, Izzy got 90 seconds, Jacob got 99 seconds, and John got 125 seconds.

First question, who actually won? Have a look at that.

Who do you think was the winner? Look at their times.

We're looking for the quickest time.

Now, is the quickest time the lowest number or the highest number? It's the lowest number.

So, who's got the lowest number? And it's Izzy.

Izzy had the lowest time, so she came in first.

Well done, Izzy.

Another question, true or false? Sophia took exactly one minute.

So there we go, she's the first one.

She took 100 seconds.

So did she take exactly one minute? What do you think? Is that true? Is that false? Is 100 seconds one minute? False.

One minute can be converted to 60 seconds.

So she took 60 seconds plus 40 seconds or one minute and 40 seconds.

Another question, who finished in under two minutes? Have a look, which of those times are less than two minutes? Might be helpful to do some conversion here, so that's what we're going to do.

So we've already worked out Sophia's time, so 100 seconds is like 60 seconds and 40 seconds.

So that's like one minute and 40 seconds.

96 seconds is like 60 seconds and 36 seconds or one minute and 36 seconds.

90 seconds, that's 60 seconds and 30 seconds.

We could convert that into one minute and 30 seconds, also known as one and a half minutes.

99 seconds, that's one minute and 39 seconds.

So 60 seconds and 39 seconds.

And John's time is 125 seconds.

That's like 120 seconds and five seconds which is the same as two minutes and five seconds.

So who finished in under two minutes? Well, basically everybody apart from John, but a good try, John.

This is Oakley.

Oh, Oakley is two and a half years old.

This is Beau.

Beau is 20 months old, and aren't they adorable? Who is older, and by how much? They've been presented in different ways, haven't they? Two different forms, so two and a half years and 20 months.

So we need to do some conversion.

So let's think about Oakley to start with.

So if one year is 12 months, another one year is another 12 months, and half a year is six months.

So that top part of the bar model, is showing two and a half years, and add all those together.

12, add 12, add six equals 30.

So we can say Oakley is 30 months, and that makes it easy to compare with Beau's age.

Oakley is 10 months older than Beau.

So converting so that the units were the same, was very helpful.

Let's have a check.

Here's Toby.

Toby is five years old next month.

How old is he now though? If he's five years old next month, how old is he now? Can you give the answer in months, and can you give it in years and months? Pause the video and give that a go.

Let us have a look.

How did you get on? Well, five years is 60 months, but he is not quite five, is he? He is almost five.

So he is now 59 months or four years and 11 months, and very well done if you've got both of those.

Time for some practise.

Sophia clears level one of Space Heroes in two minutes and 15 seconds.

John clears it in 115 seconds.

Who is quicker, and by how much? It's quite difficult to tell straight off, isn't it? So you're going to have to convert.

John's older brother is a keen long distance runner.

He starts a marathon at midday, you know what midday is, and it takes him 200 minutes.

What time does it finish? And Sophia's dad took out a 36 month contract on his mobile phone in March, 2024.

When will it end? Question four.

Would you rather have a five week summer holiday or a 37-day summer holiday? Explain.

Again, it's quite tricky to tell which is longer until you convert.

So do some conversion.

Number five, a football match is played for 90 minutes.

Got some questions.

A, can you convert that into hours and minutes? And then B, there's also a quarter of an hour break at halftime.

How many minutes is that? Then how long is the match from start to finish? So you've got your 90 minutes plus that quarter an hour, how long is it? And C, if the match starts at 15:00, and lots of matches do on Saturdays, what time will it finish? And last question, number six, have you been alive for 100 months? Work it out and explain it.

Have fun with those questions, pause the video, and I'll see you soon for some feedback.

Welcome back.

Let's have a look at some answers.

So number one, Sophia clears level one of Space Heroes in two minutes and 15 seconds, and John clears it in 115 seconds.

Who's quicker? Well, let's convert them.

Two minutes and 15 seconds equals 135 seconds.

So Johnny is quicker by 20 seconds.

And Jun's older brothers a keen long distance runner.

He starts a marathon at midday, that's 12 o'clock, and it takes him 200 minutes.

What time does he finish? 200 minutes equals three hours and 20 minutes.

So he finishes at 15:20 or 3:20 pm.

Number three, Sophia's dad took out a 36 month contract on his mobile phone in March, 2024.

Now, you might have automatically recognised that as three years, or you might have had to work it out by counting in 12s, but it's three years.

So exactly three years from March, 2024 is March, 2027.

Would you rather have a five weeks holiday or 37 day? Or five weeks is 35 days, 37 days is two days longer than that.

So presumably, you'd rather have 37 days.

I know I would.

And number five, a football match is played for 90 minutes.

Convert that into hours and minutes, that's one hour 30.

But it's quarter an hour or 15 minutes at half time.

So if we put that together, that equals one hour and 45 minutes or 105 minutes.

So if the match starts at 15:00, that's three in the afternoon, what time will it finish? It will finish at 16:45 or 4:45 pm.

You might have called it that or quarter to five.

They're all acceptable answers.

And question six, have you been alive for 100 months? Well, eight times 12 equals 96.

So when you turn eight, you've been alive for 96 months.

So on your eighth birthday, you're 96 months old.

Nine times 12 is 108, so when you turn nine, you've been alive for 108 months.

So if you are nine, you're definitely more than 100 months old.

But if you are eight, you might either not quite be 100 months old or you might just be 100 months old.

When you are eight years and four months old, you have been alive for exactly 100 months.

We've come to the end of the lesson.

I've had such fun today exploring those problems to do with time conversions with you.

So our lesson today, has been solving problems involving writing, telling and converting the time.

Time interval problems can be solved using addition or subtraction depending on the context.

So our key facts are one hour equals 60 minutes, one minute equals 60 seconds, one week equals seven days, and one year equals 12 months.

We've used those facts today, and combinations of those facts as well.

Knowing these key facts allows us to build on them to solve problems where it is necessary to convert the time from one unit to another.

It's been a real pleasure working with you today on these problems. Why don't you give yourself a little pat on the back to celebrate your accomplishments and your efforts today.

Hopefully, I'll get the chance to work with you again on another maths lesson, maybe about time, maybe about something else.

In the meantime, take care, enjoy the rest of your day, and goodbye.