# Lesson video

In progress...

Hello everyone.

My name is Ms. Safari, and I am really excited that you decided to join me today for our maths lesson.

The unit that we are studying is multiplication and division.

In the previous lesson, we learnt all about using the multiplication symbol.

In this lesson, you will learn that multiplication is commutative.

So when you're ready lets begin.

Let's have a look at today's lesson agenda.

First we will explore the commutative law of multiplication.

Then we will move onto a talk task by comparing which class is bigger.

Then we will look at arrays and the pictorial representation.

Before we begin today's lesson, you will need the following items. You will need something to write with and something to work on and you will need some cubes or counters.

If you don't have any cubes or counters, please ask your parents or carer to cut out some pieces of paper that you can use instead.

Please pause the video now to collect things that you need.

Exploring commutativity.

"Commutativity." "Commutativity." Great work! Follow with me: "Year 2 has five rows with four places in each." One, two, three, four, five.

And "Year 3 has four rows with five places in each." One, two, three, four.

I would like you to pause the video now, and tell me how many rows and places are there in Year Two, and how many rows and places are there in Year Three.

Great work! So, in Year 2 we can that there are-- let's count together one, two, three, four, five rows or five groups of four: one, two, three, four.

And in Year 3, we can see that there are one, two, three, four groups of.

five.

So we can say that there are four groups of five.

Therefore, we can say that five multiplied by four is equal to four multiplied by five.

And we call multiplication commutative.

"Commutative." Great work! Because five multiplied by four is equal to four multiplied by five.

It does not matter which way out we write them.

Let's have a look at another example: "Year Four has three rows with five places in each." "Year Five has five rows with three places in each." I would like you to tell me are these classes the same size? If so, always, sometimes or never? Pause the video now and tell your screen the answer.

Great work! So we could say that there are three groups of five, in Year Four, and there five groups of three in Year Five.

So we could say because multiplication is commutative, we know that three multiplied by five is equal to five multiplied by three.

Therefore, these classes are the same size, and they are always.

the same size.

Give yourself a pat on the back if you got that correct! So, let's have a look at another example: "Year Six has six rows with five places in each." "Reception has five rows with six places in each." I would like you to pause the video, and I would like you to write down the multiplication equation for each representation, and once you're ready we will go through the answers.

Great work! That's why they are both the same size because we can see that in Year Six there are six rows with six groups of five and in reception there are five rows with five groups of six.

So six multiplied by five is equal to five multiplied by six.

And, as we know, multiplication is commutative.

Therefore, the classes are the same size.

I would like you draw arrays for the following question: "Year Two has ten rows with three places in each.

Year One has three rows with ten places in each.

Which class is bigger?" Now I would like you to do the following: I would like you to draw arrays for the following equation, and I would also like you to write the multiplication equation to represent each array.

Pause the video to complete your task, and once you're finished, we'll go through the answers together.

So, Year Two, there were ten different rows with ten groups, and in each group there were three spaces.

In Year One, there were three rows and ten places in each.

Therefore, you could say that three groups of ten is equal to thirty or, for Year Two, you could say that there are ten groups of three is equal to thirty.

So ten multiplied by three is equal to three multiplied by ten.

If you got that correct, well done! I would also like to point out another thing about drawing arrays.

Have a look at your array, and really make sure that your arrays that you have drawn are the same as on the screen.

Make sure that each is a small dot, and that each dot are exactly underneath each other and that they are aligned, okay? It's really important to make sure that you draw your arrays correctly and accurately.

A quick check! Okay, have a look at the array at the middle of your screen, okay? Count the rows, count the groups, count the places in each group, and, after three, I would like you to point to the correct equation that is representing the array on your screen, okay? So have a good look.

Which equation is representing the array on your screen? Point after three, two, one.

Great work! Well done.

If you were pointing to answer four, you are correct because we know that multiplication is commutative.

Over here, on our screen, we can one, two, three groups of four, so four multiplied by three is the equation for the representation we can see.

Now listen very, very carefully because there a few things I would like you to do for each question.

Independent task: "Solve the word problems by creating arrays using concrete manipulatives." So the first thing I would like you to do for each question is to create, using your counters or your can use small pieces of paper-- is to create your arrays for each question.

Number one.

Number two, I would then like you to draw your arrays on your pieces of paper, okay? So you're going to draw a pictorial representation, you're going to draw your dots like the example I have here at the bottom of the screen.

And, number three, I would like you to write the multiplication equations, okay? So, like we have here, in my example.

So, we are going to read the questions together, and then you're going to use your pieces of paper or counter to create your arrays, and then you're going to draw them on your piece of paper, and you will write the multiplication equation for each representation, okay? So let's have a look at my example: "Year Six has six rows with five places in each." First thing I would do is I would use my counters and I would create my arrays here in front of me.

And, if you need to know how to do that, then please look at lesson one of our multiplication and division unit.

That's where I show you how you can create your arrays.

Then, after you have done that, you will get your pen and paper and you will draw your arrays like I have done so here, okay? And then, finally, you will your write equation for your array.

So.

Question number one.

I'm going to read each question, then you can pause after each question and complete your work.

"Year One's book corner has three rows with two places in each.

Reception's book corner has two rows with three places in each.

Which book corner is bigger?" The next question, question number two: "Year Six has ten rows with five places in each.

Year Five has five rows with ten places in each.

Which class is bigger?" Great! Let's have a look at our answers.

So, for question number one, you should have had three groups of two, which equals to six, and this is the representation and this is the equation.

And you should've had two groups of three, which is two multiplied by three is equal to six.

And we know that both are of equal size because why? Tell your screen.

Because multiplication is commutative.

Good work! And, for question number two, we know that ten rows with five places, so ten multiplied by five, or ten groups of five, is equal to fifty.

And we know that five groups of ten is equal to fifty.

Therefore, both classes, again, are the same because multiplication is commutative.

So, give yourself a pat on the back! Well done for completing your independent task, and, if you got it correctly, you've worked extremely hard and you should be really proud of yourself! If you'd like to, please ask a parent or carer to share your work on Twitter tagging @OakNational and #LearnwithOak.

And now it's time for you to complete your quiz.

That is all from me.

I hope you've enjoyed today's lesson.

Next lesson we will be looking at using the division symbol when sharing.

Take care!.