# Lesson Video: Choosing Seconds, Minutes, or Hours Mathematics

In this video, we will learn how to measure how long an activity takes in seconds, minutes, or hours and how to decide which of these units is most appropriate.

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### Video Transcript

Choosing Seconds, Minutes, or Hours

In this video, we’re going to learn how to measure how long an activity takes in seconds, minutes, or hours. And we’re also going to learn how to decide which one of these units to use.

When we measure things, we need to think about what units of measurement to use. In this video, we’re thinking about measuring time. And we can measure the time that goes by in things like weeks, months, or years. But in this particular video, we’re gonna be thinking about much shorter units of time than this. We’re going to be learning about seconds, minutes, and also hours.

Let’s start by thinking about seconds. How long is a second? Well, they’re actually very short. To give you an idea, let’s fill this 10-frame with dots. Every time you see a new dot, that’s another second that’s gone by. Ready? A second is about the same time as saying a number followed by a word like, say, elephant. One elephant, two elephant, three elephant, four, and so on. Let’s count 10 seconds together. One, two, three, four, five, six, seven, eight, nine, 10. Some analog clocks have actually got second hands on them. As well as the hour hand and the minute hand, they sometimes also have a very thin second hand. This moves once every second. And it’s what makes the sort of tick tick tick noise that you sometimes get with analog clocks. Each tick is another second.

What sort of activities could we do in one second? Well, the answer is “Not a lot.” We could blink, smile. Clicking our fingers takes about one second, just like this. Switching off the light takes about a second, but perhaps we better not do that. Can somebody take a second to put the lights back on? We’re in the middle of a video here. That’s better.

Our second unit of time that we’re talking about is the minute. You’ve probably heard this unit of time before. But do you know how long a minute is? One minute is the same as 60 seconds. So if we counted in seconds from one all the way up to 60 — one, two, three, and so on — when we got to the number 60, it would be the same as one minute. The minute hand on an analog clock face is the long one. A good game to play is to see how good you are at guessing how long a minute is. First, you wait for the minute hand to move and then start counting from one up to 60. And if you’ve counted in seconds correctly, by the time you get to 60, you’ll see the minute hand move. 58, 59, 60. Hopefully, you saw it move.

What activities could we do in a minute? It’s always a good idea to make sure we wash our hands really well. So we should wash them for at least a minute, maybe even two. Brushing your teeth might take a minute. But again, if you’re doing a really good job, maybe even longer. A minute might also be the length of time it takes to tell a joke, depending on the joke, of course. And to give you another idea of how long a minute is, so far, you’ve been watching this video for four minutes. Hopefully, this gives you some idea of the sorts of activities that we can measure in minutes.

So far, we’ve looked at seconds and minutes. And our third unit of measurement in this video is hours. Do you know how long an hour is? It involves the number 60 again. One hour is worth 60 minutes. Now, we know that the hour hand on a clock face is the short hand. And an hour is the length of time it takes to go from this position to this position. In other words, from four o’clock to five o’clock is one hour. And in the space of that hour, the minute hand goes all the way around the clock face. That’s the same as 60 minutes.

An hour is quite a long time to do an activity, so we can get a lot done. In many schools, lunch time is about an hour long, so you’ve got time to eat your lunch and then play with your friends or do whatever else you do. Your maths lesson might be about an hour long. It’s about the length of time we could bake a cake or even watch a TV program. Hopefully, thinking about these activities has given you an idea of how long a second is, a minute is, and how long an hour is.

Let’s have a go at answering some questions now where we have to choose the right unit of measurement for different activities.

At night, I usually sleep between six and nine what.

This question is is just a simple sentence. It’s about how long somebody sleeps. At night, I usually sleep between six and nine what. The way this sentence has been written, we know that this missing word is going to be a unit of measurement used to measure time. Let’s go through some different units of time and see which one makes most sense.

At night, I usually sleep between six and nine seconds. We know that a second is about the same time as it takes to clap our hands or blink or even to say a number. So nine seconds is the length of time it might take us to count to nine. I think we sleep a little bit longer than this at night, don’t you?

What about minutes? At night, I usually sleep between six and nine minutes. Now, remember, one minute is the time it takes for the minute hand on a clock to move one little notch around the clock face. A minute is worth 60 seconds. So do you think if I counted to 60 nine times, that’s as long as you’re going to sleep for? I don’t think so. It’s still too short, isn’t it?

What about hours? Is this a better unit of measurement? An hour is worth 60 minutes. And it’s the time it takes to go from one o’clock time to another. So if somebody went to bed at 10 o’clock, nine hours would be 11 o’clock, 12 o’clock, one o’clock, two o’clock, three o’clock, four o’clock, five o’clock, six o’clock, seven o’clock in the morning. This sounds about right, doesn’t it? Going to bed at 10 o’clock at night and getting up again at seven o’clock in the morning. The unit of measurement that makes most sense here is hours. At night, I usually sleep between six and nine hours.

James can stay under the water for one what. One hour or one minute?

You know, in maths, whenever we measure something, whether it’s how tall something is or how heavy or like in this question how long something takes, we don’t just give a number. We have to also have a unit of measurement. So in other words, we can’t just say James can stay under water for one because it doesn’t make sense. We’d want to say one what. And that’s why this question is all about choosing the right unit of measurement to finish off our sentence.

Can james stay under the water for one hour or one minute? Now, it doesn’t really matter whether we know James at all. This question is all about thinking about which one of these units of measurement makes most sense. To help us, let’s think about how long an hour is and how long a minute is. What do we know about an hour? One hour is the length of time it takes the minute hand on a clock face to go all the way around once. You can think of all the things you can get done in one lesson at school. That’s about an hour long. In fact, we could use this to help us. Because if we can imagine that James is having a swimming lesson, do you think he can stay under the water for the whole swimming lesson? I don’t think so, do you?

Now, we know that one minute is the length of time it takes the minute hand on a clock face to move one little notch. It’s the same as 60 seconds. So if we counted from one to 60, that’s about a minute. So which of these units of measurement makes most sense? Do you think James can stay under the water for a whole swimming lesson or for the length of time it takes to count from one to 60? I think it’s the second answer, don’t you? James can stay under the water for one minute.

Which of the following would be the best estimate for the amount of time it would take to climb a flight of stairs? 30 minutes, 30 seconds, or 30 hours?

Before we start to think about answering this question, what do you notice about the possible answers that we’re given? Can you see each of these measurements of time contains the same number, 30? But the unit of measurement, that’s a thing we’re measuring time in, is different each time. So this question is really about whether you know what a minute, a second, and an hour is.

Now, our question’s all about the amount of time it takes to climb a flight of stairs. Maybe you live in a house that has stairs in it. At the end of the night, when it’s time to go to bed, how long does it take you to get from the bottom of the stairs to the top? There’s an interesting word in this question, and it’s the word “estimate.” An estimate is a thoughtful guess. In other words, we don’t need to know the exact amount of time it takes you to walk up a flight of stairs. But what we want is a good guess, a guess that we’ve thought carefully about so that it makes sense.

Do any of these amounts of time not make sense? We know that an hour is about the length of time that you have for your lunch time every day. So do you think it would take 30 lunch times to get from the bottom of the stairs to the top? Of course, not. That doesn’t make sense, does it? That’s a silly answer. This isn’t the best estimate at all.

The answer is going to have to be 30 minutes or 30 seconds. Which is the best estimate? Well, we know that there are 60 minutes in an hour, so 30 minutes is half of an hour. Does this sound right, that you start climbing the stairs and then half an hour later, you reach the top?

Well, what about 30 seconds? We know that 30 seconds is about the length of time it takes to count to 30. Which units of measurement would make the best estimate? It’s 30 seconds, isn’t it? If we started counting from 1 to 30, it makes sense that we might reach the top of the stairs by the time we got to 30. 30 minutes and 30 hours are far too long. The best estimate for the amount of time it would take to climb a flight of stairs is 30 seconds.

What have we learned in this video? We’ve learned how to measure how long an activity takes in seconds, minutes, or hours. We’ve also learned how to decide which unit makes most sense to measure different activities.