Lesson video

Hello, I'm Miss Miah and I'm so excited to be a part of your learning journey today.

I hope you enjoy this lesson as much as I do.

In this lesson, you'll be able to use the relationship between the 2 and 4 times tables to solve problems. Your keywords are on the screen now and I'd like you to repeat them after me, multiple, double / doubling, halving.

Well done.

Let's move on.

So a multiple is the result of multiplying a number by another whole number.

To double means to become twice as many or to multiply by 2.

Halving means to divide into 2 equal parts.

So this lesson is all about the 2 and 4 times tables and how we're going to be using that knowledge to help us to solve problems. So here we've got 2 lesson cycles and in the first lesson cycle we will be using our knowledge of the 2 and 4 times tables to find the missing number.

And in the second lesson cycle we will be solving worded problems. So let's get started with the first lesson cycle.

How do you think we might be using our knowledge of the 2 and 4 times tables to solve problems? Let's get cracking.

In this lesson you'll meet Andeep and Izzy.

Let's begin, "Andeep rubbed off my number.

." And you can see there's an equation on the screen.

So we've got 1 multiplied by 8 is equal to 2 multiplied by something.

We dunno what that is.

So what advice would you give to Izzy? Explain your reasoning to your partner.

So Andeep says, "If I know that 1 multiplied by 8 is 8, then I know that 2 multiplied by 4 is 8.

This is because 1 group of 8 is equal to 2 groups of 4." So now we can demonstrate this using an array.

So there's one group of 8 and within that you can see 2 groups of 4.

later Izzy moves on to another equation and Andeeps done the same.

He's rubbed off one of the numbers from Izzy's equation.

So this time we've got 4 multiplied by 4 equals 2 multiplied by, we don't know what that missing digit is.

So again, what advice would you give to Izzy? And I'd like you to explain your reasoning to your partner.

So maybe you suggested that if you know one fact you could then use that fact to find the missing number.

But you may have said something like this.

"If I know that 4 multiplied by 4 is 16, then you also know that 2 multiplied by 8 is 16.

This is because 4 groups of 4 is equal to 2 groups of 8.

So there's 4 groups of 4 and here we've also got 2 groups of 8.

Both equations are equivalent to each other in terms of giving you the same product.

Over to you.

So now you are going to find the missing number.

You're going to show the relationship using an array.

So there is an array on the screen and it shows a product of 20.

So what you need to do is think about how you can group the array to find the missing number.

So pause the video here and when you're ready, click play to join us.

So how did you do? Well, if you know that 4 multiplied by 5 is 20, then you also know that 2 multiplied by 10 is 20.

This is because 4 groups of 5 is equal to 2 groups of 10.

You may have used your array and identified that there's your 4 groups of 5 and within that we've got our 2 groups of 10 as well.

Pairs of facts can help us to quickly solve multiplication equations.

What do you notice? Well, when one factor doubles, so does the product.

And here we can see that the 2 has doubled to 4.

So the product has doubled to 48.

Now when one factor halves, so does the product.

So in this case, the 4 has halved to 2.

So the product has also halved.

What relationship do you notice between these two multiplication equations? You may have said the same.

So when one factor doubles, so does the product, and in this case the 4 has doubled to 8, so the product has doubled to 16.

And when one factor halves, so does the product, The 8 has half to 4.

So the product has also halve.

So I'd like you to fill in the gap.

If you know that 4 multiplied by 3 is 12, then you know that 4 multiplied by 6 is.

You can pause the video here and click play when you're ready to join us.

So what did you get? If you got 24, you are correct.

And that's because we know that 4 multiplied by 3 is 12.

4 multiplied by 6, so we've doubled 3 to 6 means that our product is also going to double to 24.

Right, so Andeep and Izzy are trying to solve this puzzle.

Each symbol represents a one-digit number.

"This is hard." What advice would you give to help them to solve this puzzle? Well we know that something multiplied by something else is equal to 8.

Both numbers cannot be the same though.

That's something that we need to keep in mind.

So in this case we can use trial and improvement.

Izzy starts off by trying 1 multiplied by 8.

Let's see if that works.

So the one is going to be represented by the triangle and the 8 is going to be represented by the star.

So we've got one multiplied by 8, which is 8.

If this is one times 8 is 8, then the star shape is 8.

So now what we have to do is put that into the next question.

So let's do that now.

So we've got that there, but that doesn't work.

Why? Because 8 multiplied by 8 is 64 and it's not 16.

So one times 8 are not the correct factors for this to solve this problem.

And I'd like you to justify your thinking to your partner as well.

You can pause the video here and click play when you're ready to join us.

So what did you get it? You should have got A, and that's because if we have 2 as our triangle and 4 as the star, the first equation works.

So 2 times 4 is 8.

After that, if we then have the star as the 4, we know that 4 multiplied by 4 is 16.

Whereas if we did it the other way, the equation would be incorrect.

Right, onto your main task for this lesson cycle.

So task A, question one.

You are going to be finding the missing numbers for these equations and I'd like you to also see if you can spot a pattern.

For question B, the equations are as follows.

So 2 times 4 is equal to something times 2, 3 times 4 is equal to something times 2, 4 times 4 is equal to something times 2, 10 times 4 is equal to something times 2.

Lastly, 11 times 4 is equal to something times 2.

And question 2, you're going to solve the puzzles by finding the value of each shape.

When solving these equations, what you need to think about is trial and improvement.

You'll be thinking about what combination of factors you can put in place off the shapes to try and see if the equations are correct.

Now there are 3 examples on the screen.

The first box has a different set of combinations to the second box and the third box.

You can pause the video here.

Off you go, good luck.

So how did you do? For question one, you should have got these as your answers.

So let's go through the questions.

So 2 times 2 is equal to 1 times 4, 4 times 2 is equal to 2 times 4, 6 times 2 is equal to 3 times 4, 8 times 2 is equal to 4 times 4 and 10 times 2 is equal to 5 times 4.

Let's talk about the pattern now.

So what is happening here is as duh has doubled, the other factor has halved, which gives us the same product.

For question B, this is what you should have got.

You can pause the video here and mark your work and then click play to rejoin us.

So how did you do? If you got all of those questions correct, good job.

Now for question 2, this is what you should have got.

You can pause the video here to mark your work.

If you got all of those questions correct, well done.

It means that you are building a solid understanding in the relationship between the 2s and 4 times tables.

Right, lesson cycle 2.

This time we're going to be looking at solving worded problems. When you solve problems, you need to decide what operation to use.

Sometimes there will be more than one step with different operations.

The language in a worded problem can help us decide on the operation.

I remember in school when I had these types of questions, I used to read and read the question again until I just got confused.

And because I didn't know what to look out for and how to tackle those types of questions.

I didn't know what to look out for, I didn't know what operation I was using for the calculation.

So today I'm going to teach you how to do that, especially for multiplication and division.

So sometimes you may come across worded questions which involve multiplication or division.

To divide or to multiply? Well, so in questions you may see some of these terms; equal parts usually means you need to divide, groups of usually means you need to multiply.

Halving means dividing by 2.

Double and twice often mean we are multiplying by 2.

Split and cut often means a division question.

Times and lots of mean we will be multiplying our factors.

Identifying the keywords will help you to find which operation to use.

So Alex runs 2 kilometres each day for 3 days.

He runs 6 kilometres in total.

Izzy runs 4 kilometres each of the 3 days.

How far does Izzy run altogether? Well, in this example we are going to have to multiply and we are going to have to multiply using the information that is highlighted.

So we know that Izzy runs 4 kilometres each of the 3 days.

And how much is Izzy running altogether? Well, 4 kilometre each for 3 days means 3 groups of 4.

Altogether tells us we are finding the whole or total, which tells us that we are multiplying.

Let's have a look at this question now.

Andeep has planted 20 seeds of sunflowers in 2 rows.

How many seeds did he plant in each row? In this example, you will have to divide.

So 20 divided by 2 is 10.

And that's also because seeing each usually means that we do need to divide.

So 20 seeds of sunflowers in 2 rows means we are dividing by 2 or halving.

It also means that you are finding the missing part or quotient.

So this is the equation and we can see that the quotient there is 10 and we were halving.

Over to you.

I want you to find out what equation you are calculating based on this word problem.

You can pause the video here and click play when you're ready to join us.

So how did you do? Well, we know that the whole is 24 metres and the value of the jump is 2 metres.

So that means we are dividing 24, which is our dividend by our divisor, which is 2.

So we're halving.

So that means the monkey made 12 jumps.

Let's move on.

Andeep bakes 2 cakes a day for a party.

Izzy bakes 4 cakes.

If Izzy bakes 40 cakes in 10 days, how many days did it take Andeep to bake the same amount? Now Izzy says we must halve because Andeep baked 2 cakes a day.

Do you agree? Well, let's read this carefully because sometimes it may seem that we know what we're doing straight away, but actually we need to read the question carefully to make sure we fully understood what we are doing.

So Andeep says that he bakes half the amount, so that means it will take him double the time.

So 10 days multiplied by 2 is equal to 20 days.

So the equation that we were calculating here was 10 multiplied by 2, which is 20.

Back to you, what equation are you calculating? You could pause the video here and when you're ready, click play so you can join us.

So how did you do? So you know that Izzy bakes 4 cakes for 5 days, which is equal to 20 cakes altogether.

You also know that Andeep bakes half the amount.

This means it will take him double the time, 10 days.

So 10 days would've been your answer, the quotient.

Onto your main task for this lesson cycle.

So for this lesson cycle, you'll be completing the word problems. Question 1A is an orangutan jumps 4 metres with every jump.

A monkey jumps 2 metres with every jump.

If the orangutan jumps 48 metres, how far will the monkey have jumped with the same number of jumps? 1B, there are several rabbits in a field.

Andeep can see 28 legs.

How many eyes can he see? And 1C, Izzy is wrapping presents.

She has 32 centimetre length of ribbon.

She can make 16 2 centimetre lengths from this.

How many 4 centimetre lengths could she make instead? Chickens can be kept in coops of 2s or 4s.

If they are kept in 2s, they need 24 coops.

How many coops will they need if they are kept in coops of 4? And E, if there are 20 chickens, how many coops will be needed if each coop can hold 4 chicks? So these are the questions that you need to answer.

You can pause the video here, make sure you jot down your working and click play when you're ready to join us again.

So how did you do? Well for question 1A, the monkey would've jumped 24 metres and that's because if 4 times 12 is 48, then 2 times 12 is 24.

And that is the equation that we needed because the monkey jumps half the amount that the orangutan jumps.

For question 1B, Andeep will see 14 eyes, and that's because seven times 4 is 28.

So seven times 2 is 14.

As you know, rabbits have 4 legs and 2 eyes.

So we are going to be halving the amount.

1C, so you should have got 32 as your answer for this question.

1D, they will need 6 chicken coops because 12 times 2 is 24.

So 6 times 4 is 24.

And 1E, if there are 20 chicks, how many coops will be needed if each coop can hold 4 chicks? Well, 5 times 4 is 20.

So you need 5 chicken coops.

Well done, you've made it to the end of the lesson.

So let's summarise our learning.

Today, you used your knowledge of the relationship between the 2 and 4 times tables to solve problems. You understand that multiples of 4 are all multiples of 2, but not all multiples of 2 are multiples of 4.

You also should now understand that multiples of 4 are double the multiples of 2 and multiples of 2 are half the multiples of 4.

You are then able to use this knowledge to solve problems. I hope you really enjoyed this lesson and that it really stretched your thinking when it comes to the relationship between the 2s and 4s times tables.

I look forward to seeing you in the next lesson.