Lesson Video: Reading Clocks: Time to the Half Hour Mathematics • 1st Grade

In this video, we will learn how to tell time to the half hour on both analog and digital clocks.

16:22

Video Transcript

Reading Clocks: Time to the Half Hour

In this video, we’re going to learn how to tell time to the half hour using analog and also digital clocks. We know that an analog clock has a clock face and two hands that show the number of minutes and hours that have gone by.

Every new hour begins with an o’clock time. This is when the minute hand is pointing to the number at the top of the clock face, the number 12. You know, we can think of the numbers that go all the way around the clock as being a little bit like a curved number line. And when the minute hand points to 12 at an o’clock time, it’s almost like that minute hand is at the start of the number line ready to go all the way around the clock again.

The hour hand, which is the shorter hand, points to the hour of the day that it is. Here, we can see it’s pointing exactly to the number four. And that’s why when we see a clock that looks like this, we can read it as 4 o’clock.

But what happens to the two hands of the clock now? The minute hand will slowly make its way around the clock face. Can you see the little marks around the outside? Each one is worth one minute. And so, with each minute that goes by, the minute hand moves another notch.

But meanwhile, what’s the hour hand doing? It’s not pointing directly to the number four anymore. It’s moved. But the hour hand moves so slowly we often don’t even notice it moves. Did you know it’d moved? The hour hand moves so slowly that a whole hour needs to go by from it pointing to the number four at 4 o’clock to pointing to the number five at 5 o’clock.

Now, we already know about o’clock times, but in this video, we’re going to be telling time to the half hour. So, that includes times called half-past times as well. What do you think a half-past time looks like? Let’s speed up time until we get there. This is what we call a half-past time. Let’s think about the long minute hand to begin with. It was pointing straight up to the 12 at 4 o’clock, but now it’s traveled half the way around the clock face. Instead of pointing straight up, it’s pointing straight down.

When the minute hand, that’s the long hand, points directly to the number six, we know that it’s traveled half the way around the clock and it’s a half-past time. But how would we read this time? Half past what? We need to look at the hour hand to work out this. Where would you say the hour hand is pointing now? It’s moved on from pointing to the four, and it certainly hasn’t reached the number five yet. It’s halfway between the four and the five. You could think of it as moving halfway past the number four. And so, we could read this time as half past 4.

Now, what about the other sort of clock? You might see it at school or in your house. What does a half-past time look like on a digital clock? Remember that digital times are made out of digits. They often have two dots or squares, which we can call a colon, to separate the digits that show the number of hours from the digits that show the number of minutes. Let’s stick with our time of half past four. What might that look like on a digital clock?

We know that four o’clock looks like this. Can you see the two zeros? Remember that these tell us the number of minutes. Cause we’re starting a new hour, we’re starting from zero again. So, any digital time that ends in two zeros is an o’clock time. But let’s change our zeros to question marks because we need to think about how many minutes have gone by at a half-past time.

What will our digital clock look like at half past 4? To help us, we can think about the number of minutes that there are in a whole hour. And this is where our analog clock comes in useful. We know that the gap between one number and the next number on a clock face is worth five minutes. If we look carefully, we can see five little intervals between the two numbers, can’t we? And we can use this fact to skip count in fives really quickly around the clock face to find out how many minutes there are in a whole hour.

Five, 10, 15, 20, 25, 30. Let’s pause here for a moment. This is interesting. Remember, the whole point of what we’re doing here is trying to find out how many minutes there are in half an hour. Now, we’ve gone half the way around the clock, and it looks like there are 30 minutes in half an hour. Let’s carry on counting all the way to a full hour, and then we’ll be able to see whether we’re right. 35, 40, 45, 50, 55, 60. A whole hour is 60 minutes. And because we know that 30 and 30 make 60, we know that half an hour is 30 minutes.

And because 30 minutes have gone by at half past 4, our digital time will look like this. 4:30 is another way of saying half past 4. 5:30 is the same as half past 5. 6:30 is half past 6, and so on. The clues that tell us that these are half-past times are the minute hand pointing straight downwards to the number six and on our digital clock, it’s these digits here that show us that 30 minutes have gone by. Let’s try answering some questions now where we have to read the time to the half hour on these two different types of clocks.

Which of the following digital clocks displays the time half past 4?

To help us answer this question, we’re shown three digital clocks to choose from. These are clocks that show the time of the day using digits. In a digital time, we have one or two digits that represent the number of hours, followed by two dots, and then two digits after the dots that tell us the number of minutes that have gone by. Now, the time we’re looking for here is half past 4. Which of our three digital clocks shows the time half past 4?

We know that for the minute hand on a clock to make a whole turn all the way around, takes 60 minutes. One whole hour is worth 60 minutes. Now, if the minute hand is only turned half the way around the clock, half an hour has gone by. It’s a half-past time. And because half of 60 is 30, we know that half of an hour is the same as 30 minutes. So, if we are looking for a digital time that shows a half-past time, the minutes part of our digital clocks should show a three and a zero, the number 30.

But wait a moment, if we look at our three digital clocks, we can see that they all show the number 30. They’re all showing half-past times. We’ve got 3:30, 4:30, and 5:30. We’re going to need to think carefully about the number that we want in the hour place. We need to find the time half past four. And so, we’re looking for a digital clock where there’s a four in the hours place.

There are 30 minutes in half an hour. And so, we know at a half-past time, the number of minutes that are shown on a digital clock is going to be 30. The digital clock that shows the time half past 4 is the one that shows 4:30.

Pick the time shown by the clock. 8 o’clock, 9:30, or 8:30.

In this question, we’ve got times that are shown in two different ways. On this analog clock, which is where we have a clock face and two hands that help us to tell the time. And then, we have three times to choose from that have been written as digital times. This is where we write the time using digits and we use two dots to separate the number of hours from the number of minutes. We need to pick the digital time that matches the analog clock.

So, to begin with, let’s read the time on this analog clock. First of all, where is the minute hand pointing? The minute hand is the long hand, isn’t it? And we can see that it’s pointing downwards to the number six. We know that whenever there’s an o’clock time, the minute hand points straight up at the number 12. And so, we can see how far this minute hand has moved, can’t we? It started pointing up to 12, and it’s making its way around the clock. It’s gone half the way around the clock.

And so, we know whenever the minute hand points to the number six, it’s going to be what we call a half-past time. But half past what? To answer this question, we need to look at what the hour hand is doing. We can see the hour hand, that’s the shorter hand, is pointing in between the numbers eight and nine on the clock face. And if we look closely, it’s not pointing any position in between, it’s halfway in between. Can you see that?

So, would you say the time is half past eight or half past nine? From what we know about o’clock times, we know that at 8 o’clock, the hour hand must have been pointing to the number eight. And at 9 o’clock, it’s going to be pointing at the number nine. But it hasn’t got there yet. In fact, we could say that the hour hand has gone half way past the number eight. And that’s how we know that it’s half past 8.

Now, which of our three digital times shows half past 8? The first number before the two dots in a digital time shows us the number of hours that have gone by. So, if we are looking for the time half past 8, we need a time that shows the number eight in this position. This only leaves us with two possible answers. Can you spot which one shows half past 8?

Let’s think about the first time for a moment. And we’ll look at the digits that come after the two dots. These are the digits that show the number of minutes. When a number ends in zero zero, no minutes have gone by that hour. It’s an o’clock time. This digital time shows 8 o’clock.

Our final time shows the number 30 after the two dots. Now, this number 30 is important. Because we know that there are 60 minutes in a whole hour and half of 60 is 30, we know that the number of minutes in half an hour will be 30. This clock then shows us that half an hour has gone by since 8 o’clock. The time is half past 8.

Did you notice that although the second time was wrong, it was another half-past time, wasn’t it? 9:30 is the same as half past 9. We read the time on our analog clock as half past 8. And because we know there are 30 minutes in half an hour, we know that the digital clock that shows half past 8 is the one that says 8:30.

These strange clocks only have an hour hand. Olivia tells you that one of them shows 7:30. Which one is it?

This is an interesting question because we really have to put into practice what we know about analog and digital clocks to find the answer. Are you ready? Maybe you noticed that these two clocks were strange before we even read the first sentence. The first sentence tells us, doesn’t it? These strange clocks only have an hour hand. Remember that an hour hand on an analog clock like this shows us the number of hours that have gone by.

The hour hand moves quite slowly, doesn’t it, from one number to the next. Now, you might look at these clocks and say to yourself, “I can’t tell the time on a clock that only has one hand. I need to look at the minute hand too.” You know, this is why this question is so interesting. If we only have an hour hand, we can still tell what the time is, at least some of the time.

Let’s start by looking at what Olivia says and see how we can use this to help us. She tells us that one of these clocks shows the time 7:30. This is a digital time, isn’t it? We know that the two digits that come after the two dots tell us the number of minutes that have gone by. If ever we see the digits zero zero, it means a new hour is about to start. It must be an o’clock time.

And when we see the digits three and zero making 30 like we have here, we know that it must be a half-past time. There are 60 minutes in a whole hour. And so, in half an hour, there are 30 minutes. So, another way of Olivia telling us that one of these clocks shows 7:30 is that it shows half past 7.

To help us answer the question, let’s think about what the hour hand does as time goes by. At an o’clock time, the hour hand points directly to a number. Can you see how the hour hand in our sketch is pointing directly to the number three? It’s 3 o’clock. In fact, because we’re thinking about strange clocks that only have an hour hand, let’s rub out our minute hand. We can still tell that it’s 3 o’clock because the hour hand is pointing directly to that number. This is what 4 o’clock would look like and 5 o’clock. It’s easy to tell o’clock times when you only got an hour hand, isn’t it? We just look at the number the hour hand’s pointing to.

Now, remember, we’re not looking for an o’clock time; we’re looking for a half-past time, half past 7. To help us though, let’s think about where the hour hand would be at 7 o’clock. It would be pointing straight at the number seven, wouldn’t it? And by 8 o’clock, it would have turned around the clock face so that it was pointing at the number eight. But at the time half past 7, we haven’t got to 8 o’clock yet. The hour hand is only half the way there. It’s halfway past the number seven.

Now, which of our clocks shows that the hour hand has moved halfway between the numbers seven and eight? Our first clock shows that it’s halfway past the numbers six on its way to 7 o’clock. It’s half past 6. And on our second clock, we can see that the hour hand has moved halfway past the number seven on its way to 8 o’clock. This clock shows half past 7. Telling the time might be very tricky when you’ve only got an hour hand. But we found out there are two types of time that we can tell, o’clock times and half-past times. The clock that shows 7:30 or half past 7 is the one that shows the hour hand halfway in between the seven and the eight.

What have we learned in this video? We’ve learned how to tell time to the half hour on analog and digital clocks.

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