Lesson video

Hi, everyone.

Welcome to our lesson on near doubles.

We're going to be using our round-adjust strategy to work out near doubles.

I'm so excited, cause I love doubling numbers and I hope you are too.

So, let's get ready for our lesson.

Put on your hats.

Tighten those ties.

Tell the computer, now I'm a mathematician.

Let's get started.

So here is today's lesson agenda.

First off, we're going to look at our star words.

We're then going to do some exploring with doubling.

We're then going to practise doubling and adjusting, before moving on to an independent task and a quiz.

So, before we get started, please make sure you have a pencil, paper, and a ruler.

So let's get started.

Star words! Oh, I couldn't quite hear you, then.

Star words! That's better.

We have our near-double.

Round.

Adjust.

Strategy.

Efficient.

Now inverse we're going to go backwards, because it's the opposite.

Inverse.

My favourite.

Partition.

Because remember we're breaking up the numbers.

Partition.

Lovely.

Remember, we need to use our star words throughout this lesson.

If you see that I've forgotten, make sure you whisper at this screen, "Miss Hill, you've not used your star words." And I'll be able to hear you.

What is doubling? What can doubling mean? Let's quickly double these numbers in front of me.

Double four is eight.

Double 42, 84.

Double eight, 16.

Double 35, 70.

Double 26, 52.

Whew, well done, that was some quick five maths.

And these doubles are going to help you today.

What happens when you double these numbers? Five, 10, 20, 40.

Double five is? 10.

Double 10? 20.

Double 20? 40.

Double 40? Brilliant it's 80.

They all end in zero.

They're all multiples of 10.

And this first number five is a multiple of five.

So when we double a multiple of five, it becomes a multiple of 10.

It's pretty cool isn't it? For example, have a think of a multiple of five.

Hm, I'm going to choose 15.

Double 15? 30.

It magically becomes a multiple of ten.

Pretty cool.

So let's have a look at the number 27.

I'm going to partition this number into tens and ones.

So I have two tens and seven ones.

So I'm going to partition.

What am I doing? So here I have two tens.

Two tens, or twenty, multiplied by two, is equal to 40.

So I'm going to have to do the same to the bottom number.

So seven ones, or seven, multiplied by two is equal to 14.

Now I haven't finished that guys, I haven't finished.

I need to make sure I do 40, add 14, which is equal to 54.

So 27 multiplied by two, or 27 doubled, is equal to 54.

So you're going to have a go with these numbers, you have 26, 25, 37, 46, 39 and 49.

So what you need to do, or your steps to success, is firstly partition the number into ones and tens.

So you can use your known facts, double the ones mentally, double the tens mentally, and add them together.

We're going to pause this video before starting the task.

Great job, everybody.

Now here we have 26 add 26.

How can this calculation help me solve this one? Hmm, now I can use my round and adjust strategy, cause I know that 27 is one more than 26.

So I can double 26 and then add one.

So here I've partitioned 26 into my tens and my ones.

20 times two is equal to 40, and six times two is equal to 12.

Then I need to add them up.

So 40 add 12 is equal to 52.

Hmm.

Have I finished? I have not finished because I've only doubled 26.

I need to remember to adjust and add one.

Therefore, 26 add 27 is equal to 53.

Also, I've just had a little whisper of reminders to use my star actions, so I'm going to do it again.

So double 26 is equal to 52.

But, don't forget to adjust.

And to adjust and add one.

Therefore, 26 add 27 is equals to 53.

Thank you for the reminder.

So let's do some exploring.

It's going to be my turn doubling with regrouping, using known facts.

And I have given us a sentence down, which means this is our sentence structure that we're going to use today.

Let's have a read together.

To make a double, I'm going to mm so that both numbers are mm.

I am doubling this using partitioning.

To adjust the total I need to mm, mm add mm is equal to mm.

So I'm going to choose 15 add 16.

So to make a double, I am going to subtract one.

So both numbers become 15.

And I'm going to double this using partitioning.

So I need to partition my number 15.

And I've broken it up into tens and ones.

So 10 times two is equal to 20.

And five times two is equal to 10.

So the answer is 30.

But have I finished? No.

To adjust the total, I need to make sure I add one back on.

So 15 add 16 is equals to 31.

So this is what you're going to be doing for your independent task.

You're going to be using the for equations and the sentence stems to help you answer them.

Remember to pause this video and write out the sentence stems and solve the equations.

Good luck and see you on the other side.

Good job, everybody.

Let's go through these answers together.

So to make a double, I'm going to subtract two so that both numbers are 46.

I'm going to double, I'm doubling this using partitioning.

So 46 partitioned into tens and ones looks like this.

So 40 times two is equal to 80.

And six times two is equal to 12.

and I need to add them together, so the answer is 92.

But I need to adjust the total and I need to add two.

So the answer is 48 add 46 is equals to 94.

For our second equation, we are going to subtract one so both numbers are 36.

And I partitioned 36 into 30 and six.

30 times two is equal to 60 and six times two is equal to 12.

60 add 12 is equals two 72, but we need to remember we need to add that one on.

So the answer to 36 add 37 is equals to 73.

Our third sum, 26 add 25, I'm going to add one so both numbers are 26.

I partitioned 26 into 20 and six.

And 20 times two is equal to 40 and six times two is equal to 12.

40 add 12 is equals to 52.

But we need to remember to subtract our one.

So the answer is 51.

Therefore 26 add 25 is equals to 51.

And finally, 37 add 37.

Excuse me, 39 add 37.

So I'm going to subtract two so both numbers are 37.

I partitioned 37 into 30 and seven.

So 30 times two is equals to 60 and seven times two is equal to 14.

Then we need to add them together.

60 add 14 is equal to 74, and then we need to remember to add back two.

So 74 add two is equal to 76.

Therefore, 39 add 37 is equal to 76.

Well done, everybody.

Remember to tell yourself one, two, three, well done me.

If you'd like to, please ask your parent, or carer, to share your work on Instagram, Facebook or Twitter tagging @OakNational and hashtag LearnwithOak.

I've had a super fun lesson with you today and I can't wait to do some more learning with you soon.

Have a great rest of your day.

Take care, bye!.