Lesson video

Hello, I'm Mrs. Cayley and I'm going to help you with your learning today.

So today we are going to find a missing part when one part and the whole is known.

So let's have a look at today's lesson outcome.

Here's the outcome of today's lesson.

So by the end of the lesson, you'll be able to do this.

I can find the missing part when the other part and the whole is known.

Here are keywords for today's lesson.

Can you repeat them after me? My turn, partition.

Your turn.

My turn, part-part-whole model.

Your turn.

My turn, missing part.

Your turn.

So do you know what these words mean? First of all, we've got partition.

That means we're going to split a whole into parts.

Then we've got part-part-whole model.

This is a representation that shows the whole and the parts.

Then we've got missing part.

So we know the whole and we know one of the parts, but one of the parts is missing and we've got to find it out.

Here's the lesson outline for today's lesson.

We will find a missing part when one part and the whole is known.

So first of all, we will use a part-part-whole model to represent a missing part, and then we will find the missing part.

Let's start on the learning.

Here are some children that are going to help us today.

We've got Sofia and Jun.

So objects can be partitioned into two or more parts.

This can be shown on a part-part-whole model.

Here's a part-part-whole model.

You can see the whole has been split into two parts.

We may not always be able to see the parts.

So here, one of them has been covered up.

It's missing.

If we know the whole and one part, we can work out the missing part.

Sofia has five counters.

You can try this if you've got five counters or five objects.

How many could be in each hand? So she's going to put some in her left hand and some in her right hand.

How many could be in each hand? And she's asking a question.

"How many ways can it be done?" Here's one way that Sofia has done it.

Sofia has five counters in one hand.

How many are in the other hand? Look at the part-whole model.

Can you see there's a missing part? I wonder what it could be.

So the missing part is zero.

There are zero in the other hand.

We can see this on the part-part-whole model.

Can you see five as the whole, and five is a part, and zero is a part? Is there a different way she could have done it? Yes, here's a a different way.

Sofia has four counters in one hand.

How many are in the other hand? What's the missing part? That's right, it's one counter.

There is one in the other hand.

We can see this on the part-part-whole model.

Can you see five is the whole, and four is a part, and one is a part.

So the missing part was one.

Is there a different way she could've done it? This time, Sofia has three counters in one hand.

How many are in the other hand? What's the missing part? That's right, it's two counters.

There are two in the other hand.

We can see this on the part-part-whole model.

Can you see five is the whole, and three is a part, and two is a part? Here's a different way that Sofia has tried it.

Sofia has two counters in one hand.

How many are in the other hand? What's the missing part? That's right, it's three counters.

There are three in the other hand.

We can see this on the part-part-whole model.

So five is the whole, and two is a part, and three is a part.

Is there a different way she could have done it? This time, Sofia has one counter in one hand.

How many are in the other hand? What's the missing part? That's right, it's four counters.

There are four in the other hand.

We can see this on the part-part-whole model.

Can you see five is the whole, and one is a part, and four is a part? Is there a different way she could have done it? Here's another way that Sofia has found.

Sofia has zero counters in one hand.

How many are in the other hand? What's the missing part? That's right, it's five counters.

In the missing part, there are five in the other hand.

We can see this on the part-part-whole model.

Can you see five is the whole, zero is a part, and five is a part? So, Sofia found six different ways to partition five.

Are there any other ways to do it? I've shown the ways on the screen here.

So we had five partitioned into five and zero, one and four, two and three, three and two, four and one, and zero and five.

Do you think there are any other ways to do it? I think she's found all the ways, hasn't she? Because I can see all the numbers there from zero to five.

Sofia's asking a question.

"Would there be more ways if I had six counters?" Do you think there would be more combinations if she had six counters? Perhaps you could try it if you've got six counters or six objects to try.

Sofia found these ways to partition five counters.

So I can see the part-whole models are showing that five is the whole and we've got three is a part and two is a part, and then we've got two is a part and three is a part.

Are they the same or different? Sofia said the parts are the same but they've been swapped round.

What does the five represent? The five represents five counters in the whole.

What does the three represent? The three represents three counters in one part.

What does the two represent? The two represents two counters in one part.

Let's check your understanding.

What could the missing part be here? I can see that we have got five counters and Sofia said, "I have two counters in my left hand." Can you see two on the part-whole model? Can you see five as the whole, and two is one of the parts on the part-whole model? So let's put two counters in the left hand.

And how many counters are going to be in the other hand? What's the missing part? That's right, we've got three counters in the right hand.

So three is the missing part.

The missing part is three.

Let's check your understanding again.

What could the missing part be? I can see we've got five counters as the whole, and Sofia said, "I have one counter in my left hand." So let's put one counter in the left hand.

and we can see one is one of the parts on the part-part-whole model.

What's going to be the missing part? How many counters are going to be in the right hand? That's right.

There are four counters in the right hand.

The missing part is four.

Jun and Sofia are playing a hiding game.

Jun has three counters and has shown one hand to Sofia.

Can you see he has opened up one hand and you can see that there are two counters in one hand? Sofia will guess how many are hiding in the other hand.

Remember, the whole is three counters.

Jun is asking a question, "How many am I holding in my right hand?" Sofia said, "I think the missing part is one." Do you agree? Yes, it was one counter in the missing part.

And here's the part, part-whole model to represent the counters.

We've got three counters in the whole and we've got two counters in one part and one counter in the other part.

Jun and Sofia are playing a hiding game.

Jun has three counters and has shown one hand to Sofia.

Sofia will guess how many are hiding in the other hand.

So this time Jun has one counter in one hand and he's asking Sofia, "How many am I holding in my right hand?" Remember, the whole is three counters.

Sofia said, "I think the missing part is two." Do you agree? Yes, it was two counters in the right hand.

And there we have represented the counters on a part-part-whole model.

Three is the whole, one is part, and two is part.

Jun and Sofia are playing the hiding game again.

Jun has three counters and has shown one hand to Sofia.

Sofia will guess how many are hiding in the other hand.

Jun is asking Sofia, "How many am I hiding in my right hand?" Remember, the whole is three counters.

Sofia said, "I think the missing part is zero." Do you agree? Yes, it was zero counters in the other hand.

And there we have represented it on a part-part-whole model.

Three is the whole, three is a part, and zero is a part.

June and Sofia are playing the hiding game again.

Jun has three counters and he's shown one hand to Sofia.

Sofia will guess how many are hiding in the other hand.

Can you see Jun has zero in one hand? "How many am I hiding in my right hand?" Sofia said, "I think the missing part is three." Do you agree? Yes, it's three counters in the other hand.

And there we've shown it on the part-part-whole model.

Three is the whole zero, is a part, and three is a part.

Here's a task for you to have a go at.

Find four small objects and hold them in your hands.

So you can put some in one hand and some in the other hand and show one of your hands.

Ask a friend to guess how many you are hiding in the other hand.

So Jun is asking the question, "How many am I holding in my right hand?" And Sofia said, "I think the missing part is.

." See if you can play this game with a friend.

And use part-part-whole models to represent the objects when you played it.

So pause the video and have a go at your task.

How did you get on with the task? Did your friend guess how many counters you were hiding? So here's one example.

Jun is asking Sofia, "How many am I holding in my right hand?" Now, remember the whole is four and I can see he's got one counter in his left hand.

So what's the missing part? Sofia said, "I think the missing part is three." Do you agree? Yes, it was three counters in the missing part, and I can see it on the part-part-whole model.

Four is the whole one, is a part, and three is a part.

Did you try it a different way? Here's a different way you might have tried.

We had four counters in the whole and I can see that Jun has two counters in one hand and he's asking, "How many am I hiding in my right hand?" Sofia said, "I think the missing part is two." Do you agree? Yes, it was two counts in the other hand.

So the missing part is two.

I can see on the part-part-whole model that four is the whole, and two is a part, and two is a part.

Here's a different way they tried.

Jun has four counters in one hand and he's asking Sofia, "How many am I hiding in my right hand?" Remember, the whole is four and one of the parts is four.

Sofia said, "I think the missing part is zero." Do you agree? Yes, the missing part was zero.

I can see on the part-part-whole model that four is the whole, and four is a part, and zero is a part.

Let's move on to the second part of the lesson.

We will find the missing part.

There are two pots and five seeds.

Jun puts four seeds in Pot A.

How many seeds are in Pot B? So he's asking the question, "How many seeds are in each pot?" So we're going to put four seeds in Pot A.

So how many seeds will be in Pot B? That's right, there's one seed in Pot B.

Here it is on the part-part-whole model.

Five was the whole, four is a part, and one is a part.

Sofia said, "There is one seed in Pot B." We can check this on the part-whole model.

There are two pots again and five seeds.

June puts three seeds in Pot A.

How many seeds are in Pot B? And Jun is asking, "How many seeds are in each pot?" So let's put three seeds in Pot A.

How many are going to go into Pot B? That's right, there are two seeds in Pot B.

We can see this on the part-part-whole model.

There are two seeds in Pot B, there are five seeds in the whole, three seeds in one part, and two seeds in the other part.

We can check this on the part-part-whole model.

There are two pots and five seeds.

Jun puts two seeds in Pot A this time.

How many seeds are in Pot B? Jun is asking, "How many seeds are in each pot?" So let's put two seeds in Pot A.

How many seeds are going to be in Pot B? That's right, three seeds in Pot B.

I can see this on the part-part-whole model.

Sofia said, "There are three seeds in Pot B." So there are five seeds in the whole, there are two seeds in one part, and three seeds in the other part.

We can check this on the part-part-whole model.

There are two pots and five seeds again.

Jun puts one seed in Pot A.

How many seeds are in Pot B? How many seeds are in each pot? There is one seed in Pot A, so there's going to be four seeds in Pot B.

There's the part-part-whole model to represent the seeds.

There are four seeds in Pot B.

We can check this on the part-part-whole model.

I can see five is the whole, and one is a part, and four is a part.

This time the whole is five and one part is two.

Jun and Sofia are trying to work out the missing part.

Can you see five is the whole and we've got five seeds to represent the whole? Two is one of the parts.

What is the other part going to be? Jun said, "The missing part is smaller than five." Do you agree? Sofia said, "The missing part combines with two to make five." So that means that they can be put together to make five.

The missing part is three.

Let's check your understanding.

The whole is five and one part is three.

Who is correct? I can see that we've got five seeds in the whole and three seeds are going to be in one of the parts.

I wonder what's going to be in the missing part.

Jun thinks the missing part is three.

Sofia thinks the missing part is two.

Who do you thinks correct? Pause the video while you think about it.

That's right.

The missing part was two.

Sofia was correct.

I can see five is the whole, and three is a part, and two is a part.

Let's check your understanding again.

The whole is five and one part is four.

Who is correct this time? So I can see we've got five seeds in the whole, four seeds are in one part, and I wonder what the other part will be.

Jun thinks the missing part is one.

Sofia thinks the missing part is four.

Pause the video while you have a think about who's correct.

That's right.

The missing part is one.

Jun was correct.

The whole is five, one of the parts is four, and one of the parts is one.

Let's check your understanding again.

This time the whole is five and one part is two.

Who is correct this time? I can see five seeds in the whole, one of the parts is two.

I wonder what the missing part will be.

Jun thinks the missing part is three.

Sofia thinks the missing part is two.

Pause a video while you think about who's correct.

That's right, the missing part is three, so Jun was correct.

I can see five is the whole, two is a part, and three is a part.

Let's check your understanding again.

The whole is five and one part is one.

Who is correct this time? I can see there are five seeds in the whole.

One seed is in one of the parts.

Jun thinks the missing part is one.

Sofia thinks the missing part is four.

Pause the video while you decide who's correct.

That's right, the missing part is four.

Sofia was correct.

There are four seeds in the missing part.

The whole is five and the parts are one and four.

Let's check your understanding again.

The whole is five, and one part is zero.

Who is correct this time? There are five seeds in the whole and there are zero seeds in one of the parts.

Jun thinks the missing part is zero.

Sofia thinks the missing part is five.

Pause the video and think about who's correct.

That's right, the missing part is five.

Sofia was correct.

There are five seeds in the missing part.

Here's a task for you to have a go at.

Can you fill in the missing parts on the part-part-whole models? I can see we've got five as the whole for the top row, and then we've got four and three as the whole for some of the others.

I can see one of the parts has been shown, but there is a missing part.

Can you try to work out the missing part on the part-part-whole models? Here's the second part of your task.

Can you use the part-part-whole models to make your own missing part problems? So think of the whole to go at the top, and then put one part in and see if you can work out the missing part.

So pause the video and have a go at your tasks.

How did you get on with your tasks? First of all, you had to fill in the missing parts on the part-part-whole models.

So here are the missing parts.

I can see that we've got five has been partitioned into five and zero, five has been partitioned into three and two, five has been partitioned into two and three, and five has been partitioned into four and one.

Then we've got four has been partitioned into two and two, four has been partitioned into three and one, and four has been partitioned into zero and four.

Finally, we have three has been partitioned into two and one.

Is that what you found? How did you get on the second part of your task? We asked you to write your own missing number problems, so you might have chosen some different numbers as the whole.

I've tried, five is the whole, and four is a part, and one is a part.

Then I tried five is the whole, and two is a part, and three is a part.

Then I had four is the whole, and two is a part, and two is a part.

Then I had four is the whole, and three is a part, and one is a part.

Then I had three as the whole, and one is a part, and two is a part.

Then I had three as the whole, and three is a part, and zero is a part.

Then I had two as the whole, and zero is a part, and two is a part.

Finally, I had two as the whole, and one is a part, and one is a part.

Did you have any the same as me? Well done, we've got to the end of our lesson.

Today we were finding a missing part when one part and the whole is known.

This is what we've learned: Objects can be partitioned into two or more parts.

This can be shown on a part-part-whole model.

We may not always be able to see the parts.

If we know the whole and one part, we can work out the missing part.

And you can always use counters or cubes and the part-part-whole models to check.

Well done, everyone.

See you next time.