Lesson video

Hi there, my name is Mr. Tilston.

I'm a teacher.

Just like your teacher, I teach all different subjects, but by far my favourite one is maths.

I absolutely love it.

So it's a real pleasure and a real honour to be with you today, teaching you a lesson that's all about time, and time is a really important concept.

Now let me ask you this.

Have you ever heard your mom or dad saying something like, "Get your shoes on, we're leaving in five minutes," or maybe something like, "You need to get out of bed, it's school in half an hour." Well if so, you already know a little bit about time intervals, and that's what our lesson is going to be about today.

So if you're ready, I'm ready.

Let's begin.

The outcome of today's lesson is I can estimate and compare the duration of events and tasks.

And keywords, just one today.

My turn, interval.

Your turn.

That's quite an unusual word.

I wouldn't be too surprised if you've not heard that one before or don't know what it means, so let's have a look.

An interval is what is between two values or points.

It's not always used in the context of time, but it will be today.

So for example, the time between nine o'clock and quarter past nine is what we call an interval.

Our lesson today is split into two cycles.

The first will be estimating and comparing, and the second will be calculating durations.

So if you're ready, let's make a start by estimating and comparing.

In this lesson, you're going to meet Andeep.

Have you met Andeep before? He's a lovely chap.

He's going to be with us to give us a helping hand with our maths.

And have you met Pedro before? Pedro the panda.

Pedro's just woken up, as you can see, and he has to set off to panda school in one hour.

So does he have time, do you think, to eat a watermelon if he's got an hour? Hmm, what do you think? Could he eat a watermelon in one hour? Well, it's quite a big fruit, isn't it, a watermelon, but I think he could.

Yeah, he could probably eat that watermelon in about five minutes, knowing Pedro.

It's his favourite fruit.

Does he have time to climb a mountain? He's gotta go to school in one hour.

Can he climb a mountain, do you think? Hmm, that sounds like that would take a long time.

I don't think he has.

He could eat a watermelon, sure, but climb a mountain, I don't think so.

No, Pedro's a good climber.

Hmm, but that would take him many hours or even days.

He certainly can't do it before he goes to school.

An hour is quite a long amount of time, and there are many activities that you can do that take less than an hour.

Now there are only five minutes until Pedro needs to set off the school.

So that time's ticking, just five minutes to go.

He has time to do a quick activity.

Let's think what sorts of things he could do in that five minutes before school.

He could clean his teeth.

Yeah.

He could brush his fur.

Hmm.

He could tie his shoes.

He's just been learning to do that.

He could do that.

Pedro is considering the activities that he does and approximately how long each one might take, so roughly how long each one might take, he's estimating.

Have you heard that word before, estimating? And he's made a table.

He split it into columns, one minute, five minutes, 30 minutes, which is the same as half an hour, and one hour or more.

So Pedro's learned to tie his shoes quickly, so he could do that in about a minute.

It takes him much longer to watch an episode of his favourite TV show, "Panda Patrol." Couldn't do that in one minute, but he could do it in 30 minutes or half an hour.

It's about half an hour, a bit less per episode.

So you could watch a TV show in about half an hour.

Now, brushing his teeth takes longer than tying his shoes, but not as long as watching "Panda Patrol." It's a bit less than five minutes.

So, we can say about five minutes, approximately five minutes.

And hopefully, you also spend about five minutes brushing your teeth each time.

Three minutes, something like that.

So Pedro uses these estimating and comparing skills to add other activities to the table.

So watching a film, well, films can sometimes be a couple of hours.

Certainly an hour or more is where I would put that, approximately.

Having a swim, you could spend any amount of time having a swim, couldn't you? But for Pedro, it's usually about half an hour.

He likes to swim, so 30 minutes.

Brushing his fur, he can do that quite quickly.

That only takes him about a minute, probably a bit less.

Walking to the shop, well, the shop's not right next door to him, but it's a little bit of a walk away, but he can walk.

It takes him four or five minutes, something like that.

Now let's do a check.

Where might Pedro write eating an apple in the table? Think how long it would take you to eat an apple.

Would it take about one minute, about five minutes, about 30 minutes or half an hour, or about an hour or more? Hmm, what do you think? Pause the video.

Now, this all depends on how big the apple is, how quickly or slowly you eat, all sorts of things, so there's not a definitive answer here.

You might be a quick eater and he might be a quick eater, and it might take about one minute.

But more than likely, a bit less than five minutes.

It would certainly take more than a minute and about five minutes, I think, to eat an apple.

Time for some independent practise.

You're going to write your own examples of activities into the table.

Now, you can use some of Pedro's if you like.

You can talk about brushing your teeth and walking to school, something like that.

But try to think of your own examples as well, okay? Pause the video and give that a go.

Welcome back.

Hopefully you had the chance to talk about that with a partner as well and compare your different activities.

All sorts of things you could have put, so here's just a few examples.

So in one minute you could maybe button a coat up.

In about five minutes, you could have a shower, yeah? Takes me about five minutes.

30 minutes, could do your homework.

Again, it depends on what your homework is, but that might be a reasonable amount of time.

And an hour or more is how long you would be asleep at night for.

Ready for cycle two? Good, let's start, then.

Calculating durations.

Now, let's use our keyword, interval.

So this interval, this amount of time, is the same as quarter of an hour.

Now, you might have had some experience in the past at learning about quarter past and quarter to, and that might have made something click in your mind.

You might have seen quarter of an hour there.

It's made of three five-minute intervals.

So if you've got a 15 minute interval, that's three five-minute intervals put together, so five, 10, 15.

And it's the same as 15 minutes, a quarter of an hour, 15 minutes, three five-minute intervals, they all mean the same.

Now, this interval of time is also a quarter of an hour or 15 minutes, but it's just in a different part of the clock, isn't it? But it's still the same amount of time.

It's still taking up the same amount of space on the clock.

That's another interval of quarter of an hour or 15 minutes, a different one.

Here's another one, another interval of quarter of an hour or 15 minutes.

Here's a different one.

This one's a bit unusual, isn't it? A different interval of quarter of an hour or 15 minutes.

What's different about it? What do you think? Well, it doesn't start or end at quarter past or quarter to, it's somewhere in between.

But it's still 15 minutes.

I can still see three five-minute sections there, five, 10, 15.

So we can say quarter of an hour is a 15-minute interval of time that can start at any point.

Now, hopefully you've got some tracing paper or some very thin paper.

Andeep has, and he uses tracing paper to draw around a quarter of an hour part of the clock.

And he's going to use it later.

That's going to be really useful when he's looking at 15-minute intervals later on.

Here's what he does, puts his tracing paper on top so he can see a little bit through it, it's translucent.

He's going to draw around it.

There we go.

Take the clock away, take the pencil away and you've got a 15 minute or quarter of an hour interval.

That'll be useful later.

Now, two 15-minute intervals make a 30-minute interval or half an hour.

One, two, so that's half an hour.

And again, you probably had lots of experience in the past at learning about half past.

You might recognise that as half past, 30 minutes.

That's 30 minutes.

That's a different 30-minute interval, this time going from half past two o'clock.

It's still a 30-minute interval, though.

That's a different 30-minute interval.

Here's a different 30-minute interval, and this time it's coming from a particular minute past, not a multiple of five minutes past, but it's 30 minutes.

So we can say half an hour is a 30-minute interval of time that can start at any point.

Now, three 15-minute intervals make a 45-minute interval, or three quarters of an hour, one quarter, two quarters, three quarters, three quarters of an hour, 45 minutes.

And here's some different examples of three quarters of an hour or 45-minute intervals, and another one and another one.

So we can say three quarters of an hour is a 45-minute interval of time that can start at any point.

Do you think you're starting to get the idea about intervals and what they are? And Andeep traces around the 30-minute and 45-minute parts.

And again, that's going to give him some intervals, so he'd have three pieces of tracing paper now that's going to help him with the next activity.

Now, here's Pedro again.

So Pedro started mm at mm.

It took him mm minutes.

What time did he finish? So that's our stem sentence, okay? Well, there's a little clue there.

You might guess what he's doing, swimming.

Pedro started swimming at what? Look at the time.

What time is that? Pedro started swimming at 10 minutes past four.

Now, we don't know how many minutes it took him, so let's find out.

It took him 15 minutes.

What time did he finish? Hmm.

So we've got all the information, now we've got to work it out.

This is where Andeep's tracing paper comes in.

He's going to use that now.

He uses his 15-minute interval measurer to help him work it out.

Now, it's not in the right position at the minute, so he needs to line it up, line up the start of the measurer with a minute hand on the clock.

Now it's in the right position.

Now that's a 15-minute interval.

Now, can you see where it ends? That's what time he finishes.

The end of the measurer is on the five, or 25 minutes past.

So therefore, 10 minutes plus 15 minutes equals 25 minutes.

There we go.

He finishes at 25 minutes past four.

That interval measurer was really helpful.

Pedro started swimming at 10 minutes past four, just like before, and it's going to take him a different amount of time now.

He's had a bit longer this time.

It's taken him 30 minutes.

What time did he finish? Now, if you remember, Andeep's also got a 30-minute time measurer, interval measurer.

So this time, Andeep uses his 30-minute measurer, like so.

Can you see where that takes him to? 10 minutes plus 30 minutes equals 40 minutes, so he finishes at 40 minutes past four.

Now, we don't tend to say 40 minutes past four, do we? And you might have had some very recent experience at learning how to turn minutes past times into minutes to times, which would be more conventional.

So we could say that time as 20 minutes to five.

Yes, that makes more sense.

So what time did he finish? 20 minutes to five.

Started swimming at 10 minutes past four, and it took him mm minutes.

45 minutes this time.

Remember, Andeep got a measurer for that as well.

What time did he finish? Uses his 45-minute measurer, so he's going to line up the start of the measurer with the minutes.

There we go, and that's what time he finishes.

10 minutes plus 45 minutes equals 55 minutes.

And you can see that on the clock.

That's 55 minutes past, but we wouldn't tend to say that.

What else could we say? Have a look at the clock.

Five minutes to five, that's better.

All right, well, what about this one? He's changed his activity now.

Pedro started, what's he doing there, do you think? Rock climbing, at what time is it showing? Quarter past five.

We could say 15 minutes past five as well, but quarter past five would be the more common way to say that.

And it took him how many minutes? Let's have a look, 35.

What time did he finish? Has Andeep got a 35-minute interval measurer? No, he doesn't have one of those.

But he's confident.

He says, "I could make one but I don't think I need to." I don't think you do either, Andeep.

I could just add 35 minutes onto 15 minutes, which is what we've been doing anyway.

15 plus 35 equals 50.

There we go, but we wouldn't say 50 minutes past.

What else could we say? Look at the clock.

We could say 10 minutes to six.

Pedro finished this time, finished swimming.

So he finished swimming at what time does the clock say? Something past something, 25 minutes past four.

And it took him how long? Let's find out.

Took him 15 minutes.

What time did he start? This is a different thing, a different sort of question.

Now we know what time he finished, but we have got that 15-minute measurer again.

We could use that.

We could put that on.

This time we need to find out the start time.

You can see that on the clock now.

What time did he start? That time.

How would we say that? Well, 25 minutes take away 15 minutes equals 10 minutes.

So he starts at 10 minutes past four.

Pedro finished rock climbing at 10 minutes to six.

Hmm, I can see that on the clock.

It took him 35 minutes.

Okay, we don't have one of those, do we? I don't think we need one, though.

What time did he start? So 10 minutes to six is the same as 50 minutes past five.

Yes, it is, Andeep, good.

I can calculate this without using a measurer.

I can subtract 35 minutes from 50 minutes.

50 take away 35 equals 15.

So it would be 15 minutes past or quarter past five.

Let's have a look at a different kind of question.

Pedro started mm at mm and finished at mm.

How long did he take? Mm minutes.

Well that's different to before.

Before, we've looked at what time did he start? What time did he finish? This time we're looking at how long did he take? So he started swimming at 10 minutes past four, which is that on a clock.

That's what that looks like.

And he finished at 25 minutes to five.

So this time we know the start time and we know the finish time.

We've got to work out how long that interval was.

The 15-minute, 30-minute and 45-minute interval measurers are not helpful this time.

But you could use what you know to calculate the interval.

One strategy could be to count in five-minute intervals from the start time to the finished time.

So there's the start time, 10 minutes past, and there's a finish time, 35 minutes past or 25 minutes to.

Five, 10, 15, 20, 25, 25 minutes, that's the answer.

That's one strategy.

It's not very efficient.

A more efficient strategy is to work out the difference between the times.

The difference between 10 minutes and 35 minutes is 25 minutes.

So if we were to count on from 10 to 35, that's 25, so 25 minutes.

Let's do a check for understanding.

Solve these intervals problems. You may wish to use a clock face and tracing paper to help.

Pedro finished mm at mm, and it took him mm minutes.

What time did he start? So this is a what time did he start question.

Let's have a look at the context.

He finished rock climbing at 20 minutes to 10, and it took him 30 minutes.

So what time did he start? That's the first question.

And then we've got Pedro started mm at mm and finished at mm.

How long did he take? Mm minutes, so he started swimming at 10 minutes past five, and he finished at 10 minutes to six.

So we know both times this time, we're trying to work out how long he took.

And the last one, Pedro started mm at mm, and it took him mm minutes.

What time did he finish? Started eating, his favourite thing to do, at 25 minutes past nine, and it took him 15 minutes.

What time did he finish? Three questions.

Take your time.

Pause the video.

Good luck.

So how did you get on? Let's have a look.

The first one, that's 10 minutes past nine.

The second one, it took 40 minutes.

And the third one, 20 minutes to 10.

So very well done if you've got those right.

If not, you might need to do a little bit more practise before you start the independent activities, which are these.

Number one, create 15-minute, 30-minute and 45-minute interval measurers using your tracing paper and the worksheets.

Trace over them and use them to help work out the following.

Pedro finished walking to school at 10 minutes to nine, and it took him 15 minutes.

What time did he start? And there's a clock showing 10 minutes to nine.

So you could use your tracing paper if you like.

B, he start to walk school at 20 minutes to nine, which is there on the clock for you, and it took him 15 minutes.

What time did he finish? And then C, another type of question, Pedro started walking at quarter past four, and he finished at five minutes to five.

How long did he take? So again, you've got both clocks there.

You've got to work out the difference between those times, the duration, the interval.

And D, Pedro finished painting a picture at quarter to 12, and it took him 30 minutes.

What time did he start? And E, Pedro finished playing football at 10 minutes to six, and it took him 45 minutes.

What time did he start? For the next set of questions, there are no clocks.

So see if you can do it without.

If not, you can make the time on the clocks.

So A, Pedro started his homework at 20 minutes past five.

It took him 35 minutes.

What time did he finish? B, Pedro finished his homework at 25 minutes to six, and it took him 25 minutes.

What time did he start? And C, Pedro started his homework at five minutes past one and finished at 25 minutes to two.

How long did he take? So do make sure each time that you're doing the right thing, that you're looking for the right information.

Think about what you do know and what you're trying to find out.

Okay, good luck with that.

Again, take your time.

If you can, work with somebody else and share ideas and strategies.

Pause the video, I'll see you soon for some answers.

Did you get done with that and find it tricky or easy? Let us have a look.

So A, he finished walking to school at 10 minutes to nine.

It took him 15 minutes.

50 take away 15 equals 35, 35 minutes past is the same as 25 minutes to, so it's 25 minutes to nine.

B, Pedro started walking to school at 20 minutes to nine, and it took him 15 minutes.

What time did he finish? Well, 20 minutes to nine is the same as 40 minutes past.

So 40 plus 15 equals 55, and we wouldn't tend to say 55 minutes past, we'd say five minutes to, so that's five minutes to nine.

And C, we knew both times in this example.

We were trying to work out what that interval was.

He started walking at quarter past four, and he finished at five minutes to five.

How long did he take? Well, that's 40 minutes.

And the reason for that is the difference between 15 minutes and 55 minutes is 40 minutes.

D, he finished painting a picture at quarter to 12, and it took him 30 minutes.

So that's 45 minutes past, which is the same as quarter to, so 45 take away 30 equals 15.

You could say 15 minutes past or quarter past would be even better.

So quarter past 11 is the answer we're looking for there.

And for E, Pedro finished playing football at 10 minutes to six, and it took him 45 minutes.

What time did he start? That's five minutes past five because 50 take away 45 equals five.

Number two, the one where there was no clocks.

So well done if you did this without using a clock, but if you needed a clock, that's fine, too.

So for number two A, Pedro started his homework at 20 minutes past five, and it took him 35 minutes.

What time did he finish? 20 plus 35 equals 55, so that's five minutes to six.

Pedro finished his homework at 25 minutes to six and it took him 25 minutes.

What time did he start? Well, that's the same as 35 minutes past.

So 35 take away 25 equals 10, so 10 minutes past five.

And then for C, started his homework at five minutes past one and finished at 25 minutes to two.

How long did he take? Well, the difference between five minutes and 35 minutes is 30 minutes.

We've come to the end of the lesson.

That was quite challenging, so well done for persevering and persisting.

Hopefully you've made lots of progress today.

Our lesson today has been estimating and comparing the duration of events and tasks.

Estimating and comparing can be used when considering how long different activities might take.

This is also known as a time interval.

Hopefully you're getting expert at using that word now, interval.

Adding and subtracting skills might be used when working out intervals or durations, for example, counting on from the earliest time to the latest.

So you've used all sorts of strategies today.

Very well done on your achievements today.

You've been amazing.

Give yourself a pat on the back.

Why not, you deserve it.

Hopefully I'll get to see you again soon and we can do some more maths together.

But in the meantime, enjoy the rest of your day.

Take care and goodbye.