# Lesson video

In progress...

Hello and welcome to today's math lesson.

My name is Miss Thomas, and I'll be going through the lesson with you today.

I'm very excited and I hope you are too.

I hope you've come with lots of energy.

Let's get started with our math today.

In today's lesson agenda, first, we'll be multiplying three 1-digit numbers.

After that, we'll go to the let's explore task where you can have a practise.

Next we'll be exploring the order in which we multiply three 1-digit numbers.

And finally, you'll complete your end of lesson quiz.

For today's lesson, you're going to need a pencil, paper and a ruler.

Pause the video now and gather any equipment that you need that you haven't got already.

Here we have a word problem.

Kiara has two trays.

Each cookie has four chocolate chips.

How many chocolate chips are that altogether? Always making me hungry.

This word problem.

There are two questions for you to answer.

The first question, How might you represent this problem? And the second question, what would the equation look like? Pause the video now and decide.

Explain out loud as you answer the two questions.

Great job.

There are many ways you could have represented the problem.

You might have decided to draw the problem.

I'm going to draw mine now.

So we know we've got one cookie and it has four large chocolate chips, one, two, three, four.

There are three cookies on each tray.

There is another tray.

So there is sorry.

There are two trays altogether.

The focus of the problem is on the number of chocolate chips.

On one tray, there are three groups of four chocolate chips.

I'm going to take the chocolate chips from the tray and represent the three groups of four in an array.

This array shows the three groups of four chocolate chips.

On one tray, there is another tray.

So there is another array showing three groups of four.

Remember that the focus of the problem is on the number of chocolate chips.

To find the total number of chocolate chips, we need to find the product of three times four, twice, or we can say, three times four times two.

First to solve this equation, I times three times four, which is equal to 12.

Then I times the product 12 by two, which is equal to 24.

There are 24 chocolate chocolate chips in total.

Here we have another word problem.

We're lucky.

This one again is about chocolate chips.

So the problem says, Luca has four trays.

Each cookie has three chocolate chips.

How many chocolate chips are that altogether? Your two questions say, how might you represent this? And what would the equation look like? Pause the video and answer the questions out loud.

Great explaining.

First I know that the problem is about finding how many chocolate chips there are altogether.

I know that there are three chocolate chips on one cookie, so I'm going to draw it now when I represent it.

So I've got my three chocolate chips on my one cookie.

Next I know that there are two cookies on each tray.

There are four trays altogether.

One, two, three, four.

The focus of the problem we know is on the chocolate chips.

How many there are altogether.

I'm going to show this now in an array.

On the tray, there are three chocolate chips and there are two cookies.

So we need to group.

We need two groups of three.

There are four trays altogether.

So we need four lots of two groups of three.

My equation would be, three times, two times four.

First I would times three and two, which is equal to six.

Then I take the product six and I times it by four because that's the number of trays, which is equal to 24.

There are 24 chocolate chips altogether.

Here we have three different equations and representations.

Pause the video now and explain out loud, what's the same? And what's different? Great explaining.

You might have spotted that the factors are the same.

They are always two or three or four.

The product is always the same.

The product is always 24.

Finally, you might have spotted the order in which we multiplied those factors, two, three, and four was different each time.

Fantastic.

It tells us that it does not matter what order the factors are multiplied in.

It will results in the same product.

This is the associative law of multiplication.

Let's look at our new staff raise.

My turn associative law.

Associative law means that factors can be multiplied in any order and the product, the answer will be the same.

Let's begin or let's explore task.

There are six possible orders to the equation to find the product of two, three, and four.

Can you represent them all using an array? You could do this mentally, or you could draw an array using different colours.

You might need some different coloured pencils.

I've done one for you.

I have shown the equation three times four times two.

I have got three groups of four and they're circled in two groups.

I'm showing three times, four times two.

Pause the video now and have a go at representing the associative law.

Explain out loud why there were only six possible answers.

Pause the video and explain.

Great explaining out loud.

To use the associative law of multiplication, the factors can appear in any order and the product will be the same.

We know that now.

There are six different orders to put the factors in.

We can only swap them into six different orders.

Here we have Jake, Yousef and Ayah.

They are answering, seven times three times four.

They have all done it in different ways.

Listen carefully because you're going to have a go and decide which way you prefer.

Jake said, I would multiply three types, sorry, I would multiply seven times three, which is equal to 21 first.

I would then work out 21 times four by doubling 21 and doubling the answer.

Pause the video now and have a go at working out in the same way that Jake did.

Great.

Let's see what Yousef did.

Yousef said I would multiply seven times four, which is equal to 28 first, then to work out three times 28, i would double 28, then add 28.

Pause the video and work out the equation the same way Yousef did.

Excellent work.

Let's find out what Ayah did.

Ayah said, I would multiply three times four, which is equal to 12 first.

I would then work out 12 times seven, which is easy because I know my seven times table.

Have a go.

Pause the video and work out the equation as Ayah did.

Welcome back.

Which way, which method by which person did you prefer? call out your answer.

Fantastic.

Well, there is no right or wrong answer to this.

It's just preference.

The children have found great ways to multiply two digit numbers by one digit numbers mentally.

All methods have given the product 84.

Here's the equation seven times two times nine.

There are two questions I'm going to ask you.

You need to pause the video, think and answer them.

First question, which do you think is the easiest order to multiply the digits of this equation in? Call out your answer.

The second question says, which do you think is the most difficult.

Welcome back.

Great explaining.

I really like it when you explain out loud.

You may have found that times the greatest number first could be the easiest way as we will be left with the two that we can double the product we get.

Let's see what Yousef and Ayah did.

Ayah said, I did seven times nine times two.

I know that seven most by nine is 63.

And then I can double 63, two multiply it by two, which is 126.

The product of seven, nine, and two is 126 Yousef said, I did, Oh, he's done it differently.

I did seven times two times nine.

I know that seven multiplied by two is 14.

I can then use derived facts to find 14 multiplied by nine.

14 multiplied by 10 is equal to 140.

Nine groups of 14 is 14 less than 140, which is 126.

The product of seven two and nine is 126.

Both children got the same product at the end.

They found different ways that suited them to get the answer.

Both of them have used the associative law well.

You need to create your own three 1-digit multiplication equations.

You might like to use small pieces of paper and make your own number cards like the ones I have.

So you can fold them over and choose which ones and that will be like a surprise.

So you can make them random to make up your equations, or you can choose yourself from the number cards we have here.

Remember think carefully about the most efficient way to solve the equation.

Think about the order you want to put those digits in.

Welcome back.

You've had a go independently at creating three 1-digit multiplication equations using the digit cards.

Now there are lots of possible combinations you could have used.

So I've put some examples of correct answers on the slides for you on the video.

However, you might not have the same combinations as I do.

So you might need to ask somebody to check for you or check with a calculator.

The time as come to complete your end of lesson quiz.

Go away, get your quiz and show off just how much you've remembered about the associative law.

Well done.

You've made it to the end of the lesson.

Fantastic work today.

See you next time.

Bye from me.