Lesson video

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I'm Mr. Coward.

And welcome to today's lesson about fractions and units of measure.

For today's lesson all you'll need is a pen and paper, or something to write on a with.

Please take a moment to clear away any distractions, including turning off any notifications.

And if you can, please try and find a quiet place to work, where you won't be disturbed.

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

Okay so time for the Try This task.

What fraction do the red and blue arrows show on the number line? Okay what you need to be thinking about here, is how many equal parts are there? How many equal parts are there in a whole? That will help you out a lot.

Okay, so I would like- I want you to pause the video and have a go.

Pause in three, two, one.

Okay, so here are my answers.

Now I'm going to talk through them.

I'm going to talk where they come from.

So this first one, how many equal parts are there in a whole? There's one, two, three, four, five.

So that is why the denominator is five, because there's five equal parts in a whole.

And how many equal parts is there in that red arrow? One, two, three.

So that's three equal parts.

Now, this one, we can think of it as one whole, two wholes, and 2/5, so two out of five equal parts.

Or we can think of it as one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve.

Twelve parts.

So hopefully that makes sense.

Okay, now, a glass mirror has an area of one metre squared.

So that whole represents one metre squared.

So what area would this be? Well that is 1/4, because it it one out of four equal parts.

So that would just mean my area here for this one would be 1/4 of a metre squared.

And here we've got one, two- two whole ones and one, two, three, four, five, six, seven- 7/8.

So we've got two whole one and 7/8 metres squared.

So now we're thinking about fractions as units of measure.

So if that is the whole, if one metre squared is the whole, what is 1/4, what is 2 7/8? So that's why we need our units as well.

Okay so I'd just like you to have a think so- and see if you can work out what each fraction of one litre of orange juice is shown.

So pause the video and have a go.

Pause in three, two, one.

Okay so hopefully you've had a go, and here are my answers here.

So what have I got? I've got one out of two equal parts, so it's 1/2 a litre.

A whole and one out of six equal parts of a litre.

Two wholes and 1/3 of a litre, so two whole litres and 1/3 of a litre.

And if you wrote them as improper fractions, where the numerator is bigger than the denominator, so for instance on this one if you wrote that as 7/3, that is- of a litre- that is also correct.

Okay so, we're going to start to change it up now, where the whole might not be one.

What fraction of the flag does each colour take up? Hmm, can you see? Well the orange is 1/2 of the whole.

And this one is 1/4, this one is 1/4.

So if the flag was one metre squared, what area does each colour take up? Well this one would be nought point five metres squared, or 1/2 a metre squared.

This one would be 1/4 of a metre squared, and this one would be 1/4 of a metre squared.

Okay so that's quite straightforward, but now, what if the area was two metres squared? So the whole area is two metres squared.

So this would be 1/2 of 2 metres, this area, which would be 1 metre squared, okay? Because the whole thing is 2 metres squared, so half of that would be 1 metre squared.

And what would this be? Well that's 1/4 of the shade, so 1/4 of 2 metres is 1/2.

1/2 is one, so 1/2 of 1/2 is 1/4, so 1/4 is 1/2 a metre squared, and the same for this one.

What if it was three? Well three is a bit trickier isn't it? So represents 1/2 of three.

So what is 1/2 of three? Well I could write it as 1 1/2, but I think this is probably slightly easier, if I write this as 1.

5, okay? So if I write that as a decimal.

1 1/2 is the same as 1.


And we mustn't forget our units.

So now this- well 1/4 is 1/2 of 1/2, so what is 1/4 of 3 metres squared? Hmm, what is 1/2 of 1/5 metres squared? 0.

75 metres squared.

So can you see how different- what's different now? That fact that we've got a different number representing the whole.

So for instance if the whole was eight metres squared, the area of each colour would change.

If the whole was 20 metres squared the area of each section would change.

So now we're kind of thinking about what is the whole? How much is that worth? How does that affect how much an equal part is worth? Okay so what I'd like you to do is have a go at the Independent Task.

And there's three questions here.

So pause the video to complete your task.

Resume once you've finished.

Okay and here are my answers.

You may need to pause the video to mark your work.

Okay, awesome.

So it's just time for the Explore Task now.

Now if you need a hint, I'm going to give you a hint, however I want you to have a go first.

So pause the video to complete your task.

Resume once you've finished.

Okay so here is my hint.

Well, where would- so 60 seconds is all the way around.

60 seconds is the whole.

So 1/2 of a minute would go to here.

How many seconds is that? What is that angle? For 270 degrees, 270 goes around to here.

That's 270.

How many seconds is that? What fraction of a whole is it? What fraction of one minute is it? 20 seconds.

Where would that go? Hmm, how could we work out that end goal? What would this angle be? And this one, and this one.

Between each number what would the angle be? Well we've got 60 seconds, sorry- We've got 360 in the whole.

Each part is 1/12 of that.

So each part would be 30 degrees.

That should give you a bit of a hint there.

And then the final one.

The final one is very tricky.

So if we had 60 seconds in a minute, 60 seconds would be the whole.

So what would be 1/5 of the whole? Well we divide that by five and that tells us what 1/5 is.

So then how would we find 2/5? Hmm, so have a go and see if you can work that out.

Okay, so have a go and come back for the answers once you're done.

Okay so here are my answers.

I'd like you to mark your work.

Really well done if you've got that correct.

And that is all for today's lesson.

So thank you very much for all your hard work.

I am- don't forget to complete the quiz after the lesson, and just thank you very much and I hope to see you next time.