Lesson video

Hi everyone, my name is Miss Sabzvari and I'm really excited you decided to join me today for our math lesson.

The unit that we're studying is time.

In the previous lesson we focused on calculating the duration of time in minutes.

In this lesson, we will be calculating the duration of time in hours and minutes.

So, when you're ready let's begin.

Great, so let's have look at today's lesson agenda.

First we'll begin by calculating end times and events.

Then we'll move on to a talk task.

After that, we'll be calculating the duration of events.

And finally, you will complete your independent task.

And before we begin today's lesson, you will need the following items. You will need something to write with and something to write on.

You will need a clock, and finally, you will need a ruler.

So please pause the video now and get the items that you need.

Calculating end times.

Let's have a look at the word problem on our screen.

Follow with me.

Jack started the race at 10 past three.

He finished one hour and five minutes later.

What time does he finish the race? What I would like you to do is to pause the video and to tell your screen what is known and what is unknown.

Do that now.

Great job.

So we know that the race started at 10 past three, so we know the start time.

And we know the duration of the race.

We know how long the race lasted for.

Okay.

And what we've tried to work out is what time it finished.

So, what I would like you to do is to show the time 10 plus three on your clock and to work it out.

Then we will go through the answers together.

So, I know that Jack's start time was 10 past three.

So I'm going to show 10 past three on my clock.

Okay, so that's 3:00, and five, 10.

This is 10 past three, okay? And he finished one hour and five minutes later.

I know that one hour from now the minute hand needs to make a full turn once.

So this is one hour.

And five minutes, so I need to keep on going for another five.

So, I know that Jack finished the race at quarter past four.

Great job, so it's a quarter past four.

Let's have a look at another word problem.

Follow with me.

Mary started the race at 10 past three.

She finished one hour and 10 minutes later.

What time did she finish the race? Again, what I would like you to do is to pause the video and to tell me what is known and what is unknown.

Do that now.

Great job.

So we know the start time, which was 10 past three.

And we know the duration of the race which was one hour and 10 minutes.

And what we're trying to work out is the time that she finished the race, so the end time.

Now, what I would like you to do is to show the time on your clock and to work it out.

Then we'll go through the answers together.

So our new answer is 20 past four.

And I know this because the race started at 10 past three.

So in order for an hour to happen, the minute hand needs to make a full turn.

Okay, so now it's 10 past four.

And then the race went on another 10 minutes.

Okay? So from where I am, I'm going to add another 10 minutes.

So skip count with me.

Five, 10.

So, the end time of the race was 20 past four.

Great job.

So, let's have look at our talk task.

What I would like you to do is to show the start time on your clock.

Then I would like you to count the duration in five minute intervals.

And finally, I would like you to say and write down the end time, okay? Do that now.

Great, let's have a look at the answers.

So, I know that Laura started at 20 past six, okay? And the duration of her race was one hour and 10 minutes.

And what I want to know what time it ended.

So, from 20 minutes, the minute hand is going to make one full turn until where it is, so that's one hour.

And I need to add another extra 10 minutes.

So, five, 10.

So I know that Laura's end time is half past seven.

Great job.

Looking at Becca, I know the start time with Becca was 20 past seven.

And the duration of her race was one hour and 10 minutes.

Therefore, again from where the minute hand is the minute hand is going to make one full turn and now it's 20 past eight.

And we need to add another extra 10 minutes.

So, five, 10.

It's now half past eight, good job.

And finally, John.

The start time for John is 20 past seven, too.

And his race lasted one hour and 15 minutes.

So one hour is going to be 8:20, or 20 past eight.

And another 15 minutes is going to be added on.

So, five, 10, 15.

So John's end time was 25 to nine.

Great work.

Calculating duration of events.

So, let's have a look at the table on our screen.

What we can see again, are our runners, okay? And here we have got the durations so we know how long the race went on for.

And we know what time they finished.

What what don't know is what time they started.

Okay, so that's what we're trying to work out.

So, what I would like you to do is to pause the video and to tell me how can we work out what time the runners started their race Do that now.

Great work, so we can show the time, the end time, on our clock.

And we can work backwards, okay? And then we will find the start time.

So, what I would like you to do is to pause the video and to find the start time.

And to draw the clocks for each person, and then we will go through the answers together.

Do that now.

Great, so in order to work out Alice's start time I know that her end time was 25 to five.

So I need to show 25 to five on my clock.

So this is showing 5:00.

So, 5, 10, 15, 20, so 25.

Okay, so this clock is showing 25 to five.

And in order to work out to the start time I know that I need to go backwards.

I need to go anti-clockwise for the duration of one hour and 10 minutes.

So, in order to show one hour I need to go around the clock in the opposite direction once okay, so one full time.

That is one hour.

And I need to take away another 10 minutes because the race lasted one hour and 10 minutes, okay? So, five, 10.

So the race started at 25 past three.

Good job.

Now, moving on to Becca, I know that her race ended at 25 to five.

So, I'm going to show 25 to five on my clock.

And I know that her race lasted one hour and 15 minutes.

So again, I'm going to take away one hour and I'm going to take away another 15 minutes.

So 5, 10, 15.

So I know that her race started at 20 past three.

And finally, John.

I know that his race also started at 25 to five, so I'm going to begin on 25 to five and I'm going to take away one hour and 20 minutes.

So one hour, and 20 minutes this time.

So 5, 10, 15, 20.

So his start time was quarter past three.

Great job, so just like we saw Alice's start time was 25 past three.

Becca's start time was 20 past three.

And John's start time was quarter past three.

Great work.

Now, let's have a look at this table.

This time we know the start time and we know the end time.

But what we don't know is the duration of the race.

And what I would like you to do is to pause the video and to tell me how can we work out the duration, do that now.

Great job, so we can show the start time.

And then we can skip count until the end time, okay? So, pause the video and work out the duration of the races, then we'll go through the answer.

Great, so this time we're working out the duration of the races.

And I know that Sarah's time was quarter to four.

So I'm going to show that on my clock.

So this is 4:00, and this is quarter to four.

Okay, and I know that the race finished at five to five.

Okay, so I know if the clock makes a full turn it's going to be quarter to five.

And that is one hour.

And I know I need to keep going until I reach to five to five.

Okay, so one hour and five, 10.

So the duration of the race was one hour and 10 minutes.

And moving on to Becca, I know that her start time was 10 to four.

Okay, so this is 4:00, this is five, 10 minutes to four.

And her finish time was five to five.

So I know that if my minute hand makes a full turn it's going to be one hour and it's going to be 10 to five.

Okay, and I need to add another five minutes so the race lasted one hour and five minutes.

Great work.

Great job.

So as we saw, Sarah's race lasted one hour and 10 minutes.

And Becca's race lasted one hour and five minutes.

Great work.

And moving on to independent task.

What I would you to do, is to fill in the missing values on the race table.

Then, I would like you to use your clocks to calculate the answers.

And finally, I would like you to draw the minute and hour hands on the clocks.

Or, to complete the start time, the duration, and the end time.

Once you're ready, we'll go through the answers together.

So let's have a look at the answers together.

We know that Laura's start time was 20 to eight.

Okay, and her race lasted an hour and 20 minutes.

So, 20 to eight, and hours time is going to be 20 to nine.

And adding 20 minutes, 5, 10, 15, 20.

So it's going to be 9:00.

Great work.

And we don't know Becca's start time so what we're going to do is we're going to work backwards.

Okay, we know that her end time was five past eight, okay.

And the race lasted one hour and 20 minutes.

So I'm going backwards.

It's going to be five past seven, and then taking away 20 minutes.

So 5, 10, 15, 20.

So quarter to seven, good work.

And moving on to John.

We know that his start time was 20 past four.

Okay, and we don't know the duration of his race but we know that the end time was five to six, okay? So, we know that in order to work out the duration we need to make one full turn.

So 20 past four, one full turn, 20 past five.

And then we need to keep going until we reach five to six.

So, 5, 10, 15, 20, 25, 30, 35, great work.

So the duration of his race was one hour and 35 minutes.

And if you'd like to, please ask your parent or carer to share your work on Twitter tagging @OakNational and #LearnwithOak.

And now it's time for you to complete your end of lesson quiz, take care.