Lesson video

Hello, my name is Mrs. Behan, and for this lesson I will be your teacher.

In this lesson we will learn how to use a stopwatch correctly.

We will look at a bad example of using a stopwatch, and then good examples of using a stopwatch.

It may be useful to ask an adult to come and help you through this lesson.

Let's begin by looking at the lesson agenda.

First, we will make numbers 100 times greater, just for good practise.

Then we will learn how to use a stopwatch.

Then we'll practise timing some activities.

And after that there'll be an independent task for you to have a go at.

I will go through the answers with you because I know you'll keen to find out how you got on.

There are a few things that you will need for this lesson.

Something to write with.

So a pencil or a pen.

Something to write on.

You will also need a stopwatch.

Now these can be found online.

So an adult will need to help you find an online stopwatch.

Most devices like tablets and phones also have stopwatches, but again you do need an adult help.

So for that reason, make sure you grab an adult.

If you don't have those things to hand right now, just pause the video whilst you go and get them, when you're ready comeback and we'll start the lesson.

Try to work in a quiet place where you won't be disturbed.

Let's warm up our brains with a quick mental math activity.

We're going to make numbers 100 times greater.

And remember the secrets of multiplying by 100 is to move the digits two places to the left, and then you see zeros as placeholders in the tens and ones places.

Are you ready? Let's go.

One made 100 times greater is 100.

Three made 100 times greater is 300.

Six made 100 times greater is 600.

Two made 100 times greater is 200, well done.

Four made 100 times greater is 400, and nine made 100 times greater is 900, well done.

Eight made 100 times greater is 800.

Seven made 100 times greater is 700.

And five made 100 times greater is 500, excellent job.

What's 10 made 100 times greater? 10 made 100 times greater is 1,000.

We actually have three zeros there as placeholders, a zero in the hundreds place, the tens place, and the zeros place.

Okay, so let's get stuck in to the main parts of our lesson about stopwatches.

So firstly, what is a stopwatch? Well, a digital stopwatch like you can see on the screen is something that we use.

It's a tool that we use to measure how long something takes.

So the time taken to complete an activity.

The stopwatch measures in minutes, seconds, and milliseconds.

They need to be used properly.

Michael and Zara are learning to use a stopwatch.

Michael has the stopwatch, and Zara is going to do some star jumps.

Michael is going to count how many star jumps Zara can do in 10 seconds.

The video shows the stopwatch that Michael used.

As soon as the video plays, imagine that that's when Michael said go to Zara.

So she starts doing her star jumps straight away.

At the end of the video, we will discuss what advice you might give to Michael.

What do you think about the way Michael used the stopwatch? Was it a good example or a bad example? I think Michael needs a bit of advice.

There were a few things that were wrong in the way that he used his stopwatch.

Did you notice that there seem to be a few seconds once the video have started, where that perhaps that like your screen had frozen? Well, Michael had actually started the stopwatch.

Even those Zara was told to start jumping.

So it's really important that the stopwatch is started as soon as the activity was started.

Michael also kept pressing stop and start throughout the activity.

So there's some times where actually time has been frozen on the stopwatch, before we started it again.

So Zara could have been doing star jumps in that time, actually having longer than 10 seconds to do her star jumps.

So at the end the result is not going to be accurate.

And also the timer after the given time was given.

So Michael said to Zara that she could have 10 seconds.

Well, the display is still carried on after 10 seconds.

So it's important that if you're saying you can have 10 seconds to do something, then you stop the activity at 10 seconds.

So, what should we do? Well, we should always start the stopwatch when the activity begins.

We should not stop and start the stopwatch once the timing has started.

It will give us an inaccurate result.

And we should make sure that the full time is given before stopping the timer.

If you stop too early, your result will be inaccurate.

If you stop too late, your result will also be inaccurate.

So these are the three main points.

Start the stopwatch when the activity begins.

Do not stop and start the stopwatch once it started, and make sure the full time is given before stopping the timer.

So it's clear to see that you will need to concentrate when you are using a stopwatch.

If you have a stopwatch, here are some activities that you can have a go at.

Write your name out neatly three times, and see how long it takes you.

So you should start the stopwatch once you've started writing your name, and as soon as you're finished, stop the stopwatch and see how long it took.

This is where you might need a friend or an adult to help you.

List the multiples of four up to four times 12.

See how long that takes.

Sing happy birthday twice.

Just do it quietly.

And count to 100 clearly.

So use your stopwatch carefully with the help of an adult, or somebody else and have a go at these activities.

There's a challenge as well if you manage to complete those on screen.

Time someone else doing the same things, and compare how long it took each of you to do the task.

If you do not have a stopwatch, you can use this one on the screen.

So you can still do the same activities as if you have a real life stopwatch.

But what I will do is I will press play on here.

And this shows you, this is a time for one minute.

It shouldn't take you any more than a minute to do the things listed.

If you need to use a timer again, you can just go back to the point where the timer starts again.

Okay, here it goes.

Now that you've practised using a stopwatch you ready to do the independent task.

Please estimate the time it will take to complete these activities and then time yourself.

Sing the alphabet song.

How long do you think it's going to take you? Write that under the estimated time.

Then time yourself singing the alphabet song using a stopwatch.

Then you can record the actual time on your sheet.

Get yourself a drink of juice, and write a thank you card to somebody.

So estimate the time and then record the actual time.

Pause the video here whilst you complete your task.

And then we will go through some answers together.

So it's important for me to point out that here the time it took me to do something might be different to the time it takes you to do something.

But I did estimate, and then I timed myself using a stopwatch.

So I estimated that I could sing the alphabet song in 20 seconds.

And I timed myself it actually took me 24 seconds.

So did it take me longer or less time than my estimated? It actually took me more time.

It took me four seconds longer than my estimated.

To get myself a drink of juice, I estimated that this would take me 45 seconds.

My actual time was just 28 seconds.

So I was actually a lot faster than I thought I was going to be.

And how long did it take to write a thank you card to somebody? Well, I estimated 30 seconds, but actually it only took me 17 seconds.

I could write about three thank you cards in one minute.

If you'd like to, please ask your parents or carer to share your work on Instagram, Facebook or Twitter, tagging at @OakNational, @LauraBehan21, and hashtag LearnwithOak.

I hope you had fun doing those activities with me.

I know I had fun, and I know that it takes me less than 20 seconds to write a thank you card.

I can get loads written in a very short amount of time.

I think I'll go and do that now.

See you again soon, bye bye.