Lesson video

Good morning, welcome back to Oak National Academy, and am Ms. Brink We going to be carrying on learning about fractions today.

Today, we're adding fractions with the same denominator, and this will be building on your fraction work that you've been doing over the last few weeks.

So let's get started.

Same as usual you don't need much just paper or a pen anything to write on, just pause the video here if you need to go and get that.

Once you've done that again, pause the video if you haven't already done the introductory quiz, which will be some revision on yesterday's lesson.

Let's come back together then.

Oh, a nice warm up here, a little bit of revision.

Look at that lovely bar chocolate, would you rather I gave you half of that bar of chocolate? or a quarter of that bar of chocolate? Which would you prefer? Once you write that out, how many pieces do you think you're going to get If you've chosen half or a quarter? Pause the video and have a go at those two questions.

Would you rather have a half or a quarter? And how many pieces will you get? Looking at that beautiful bar of chocolate then.

Assuming that you like chocolate, the answer to get the biggest part the greatest part of that bar of chocolate would be half.

Half is bigger than a quarter.

Now sometimes that could seem a little bit confusing because two is normally smaller than four, but we know when we're looking at unit fraction that those fractions that have one as their numerator.

The bigger the denominator the smaller the fraction.

Why is that? Why would we rather have a half than a quarter? Well the best way to think about this is if you get half of that chocolate bar, you are sharing it with just one other person It is being shared equally between two people 'cause you're going to get half of that chocolate bar.

If you get to quarter the chocolate bar, that's like sharing it equally between four people, and so you'll get a much smaller part of the chocolate bar.

So how many pieces are you going to get? Let's have a good look at that chocolate bar.

If I think about cutting that chocolate bar vertically or horizontally split it into two equal pieces.

How many pieces of chocolate are you going to get? Wow, it looks like there's eight in total, so if you're going to get half of that it's four.

So if you chose half the chocolate bar, you're going to get four pieces of chocolate.

If you chose to have a quarter of the chocolate bar and we can see that it's sort of split into quarters that play.

So we've got four sets of chocolate pieces going down, you would get two pieces of chocolate if you chose to have a quarter at that chocolate bar.

Okay.

Let's move on then and we'll go on to our star words I'll say them and then you can say them at home.

So we've got nominator, altogether, whole, add, numerator, plus, fraction.

Now some of these we've been talking about all week.

Others the three on the right altogether, add and plus, those are new to our fraction word today.

Probably not new to you but new to fractions, and that's because today we're looking at adding fractions with the same denominator.

What does this look like then? Have a look at this image here, what's being shown? And what can you see? How many parts has this shape been cut into? That's not too hard, this shape has been cut into four parts, four equal parts.

That is going to become our denominator.

So the number of equal parts that this shape has been cut into or a number becomes the denominator.

There are four in total.

How many green parts are there? This isn't too hard, there are two green parts.

And how many purple parts are there? There's one purple part.

What does this look like then in terms of adding fractions? Well we can show it like this two quarters.

There are two green parts, that's two quarters.

Add it to one quarter, that's one purple quarter two quarters add one quarter.

let's see what happens when we add together two quarters and one quarter.

We get three quarters.

Now hopefully you can see that it's just the numerator which we add together, two add one is three.

We do not add together the denominator.

This is because the shape is still cut into four equal parts.

We just added some of those together.

Let's try again, let's do the same thing with this shape here.

Let's see how many equal parts we've got for this shape, the denominator.

How many equal parts are there? Well, let's have a count one, two, three, four, five, there're six equal parts.

That's our denominator for this question.

Let's have a look at how many different colours and how that's split up onto this shape.

How many red sections are there? Two.

How many yellow? There are three yellow.

So how we look at adding these two fractions together? What does that look like then? We found our denominator and our numerators.

Let's see what that looks like to add together.

All together, two sixths is our red part and three sixths is our yellow part.

What do you think the answer is going to be when we add those together? Two add three is five, five over six.

And we can see again the the denominator doesn't change.

Let's work out a success criteria then, for when we're adding fractions with the same denominator.

What have we been doing first? We found the denominator by counting the total number of equal parts.

What do we do next? That's three in this question, there are three equal parts if we look at this bar here.

Identify the parts coloured, one blue and one pink on this question, and then just add them together.

What does that look like? One third add one third is two thirds.

So just have a look at that success criteria for today.

Find the denominator identify the parts coloured add them together.

Remember just adding the numerator not the denominator.

Okay.

Your turn then, have a look at this question.

Why is it that we don't add the denominator? Why don't we add the denominator? The top answer is correct, and the bottom answer is incorrect.

Why is that? Why do we just add the denominator? Well if you look at the triangle there, the number of equal sections hasn't changed.

We still have three equal sections we just added them together.

So we've had one third is yellow and two thirds are white, If we add those together we have three thirds.

Our triangle is still split into three equal parts.

The answer underneath is wrong, we don't know have six equal parts.

Okay so we're going to be looking at this part whole model today, to help us with our adding of fractions.

Now we know that there are five fifths in total on this shape, but the right ones are two sorry, the yellow ones are three fifths and the red ones are two fifths.

So we can use this part whole model, we've got the whole there on the left, which is five fifths and then we have the parts here in the other two circles.

So three fifths and two fifths is five fifths.

Why don't you have a go? What's being shown here in the red sections? In the blue sections? And then how much is that altogether? Have a go.

Okay, if we look at the shape, the red sections are three sevenths.

We have some seven sections altogether and three of them are red.

The blue is two sevenths.

Seven we still have seven sections altogether and two of them are blue.

If we add those together we just have to add together the numerators.

Three and two is five.

Okay.

Does the order matter when we adding together fractions? Let's have a look.

We've just done that three sevenths add two sevenths is five sevenths.

Would we have got the same answer if we'd done two sevenths and three sevenths? Yes we would.

And this is because it's the same when we add any two numbers together, it doesn't matter which order we add them in.

If you think two add three is five and three add two is five, it doesn't matter the order when they're adding these fractions together.

Okay.

We're going to pause here and it's time for you to do the main activity, but I will go through the first one with you just to show you what we're doing.

So your main activity looks like this.

And for the first section, you can see that one's been started for you.

So we've got one quarter is in yellow and in fact, another quarter is in yellow as well.

So for this question, I've got one quarter add one quarter, one quarter add one quarter, I just need to add my numerators together and I get two quarter.

Pause the video here and have a go at the rest of the questions on your worksheet.

Coming back together let's have a look at these answers then.

For the question B.

What is the denominator? How many pieces are there in total? Well, there are one, two, three, four, five, six, seven, eight, nine, 10.

Our denominator for question B should be 10, and that doesn't change.

So in that first bar I have six tenths in yellow.

In the second bar I have two tenths in yellow, six add two is eight.

I have eight tenths all together.

Don't worry if you haven't used the part model to answer it, as long as you've got the answer eight tenths that's absolutely fine.

Looking at the question below, how many sections do I have altogether? I have a denominator of nine and my blue sections are two, two ninths.

My pink sections are four, four ninths.

What is two add four? I've got six ninths for that question.

Okay, let's move on to part B, so add these fractions.

So five add two is seven, you should have seven eighths for that question.

And you could draw a picture to help you if you need it to.

For B, you need to do a little bit of working out.

What is your denominator? Your denominator is those all the first little sections underneath.

So your denominator for this question is six.

That bar is cut into six equal pieces.

How many of them are blue? There are three blue sections, two red sections and three add two is five, five sixths.

So if you got a little bit confused from that one, 'cause it's a little bit tricky to see that it's split into six.

So if you got a five sixths maybe you missed out that last section at the end of the bar.

Four sixths add one sixths is five sixths.

And for our last question, five sevenths add two sevenths is seven sevenths.

Pause the video here and have a go at that final quiz, where you can revise what you've learned today.

Fantastic work today everybody.

Hopefully that's made adding fractions with the same denominator a little bit clearer for you.

Thank you very much, bye bye.