Lesson video

Hello everybody and welcome to today's session.

My name is Ms. Hughes and in today's lesson, we're going to be using our number bonds to 20 to help us with subtraction.

So let's get going.

Our lesson agenda for today is going to look something like this.

We're going to start off with using some number bonds, within 10 and looking at those, then we're going to play a spinner game.

Next, we're going to use some number bonds within 20, and finally you'll have your main task and quiz to complete.

For today's session, you are going to need these things.

You're going to need to get a pencil, a piece of paper and you are also going to need a spinner and a paperclip to help you use your spinners.

You can either draw these out, or you can go to our downloadable resources and print those spinners out.

You might want a parent or carer to help you get these things, but pause the video now to get them if you haven't got them already.

Brilliant, let's start off with the number bonds today then.

So you will notice in our part-whole models on the slide today, there are some number bonds to solve.

You've been given a whole and a part, and you need to figure out what part is missing.

Brilliant guys, let's go through those answers.

So remember you have been given one of the wholes, oh sorry, the whole and one part.

And one of these parts is missing.

Remember in a part-whole model, we add our parts together and they make our whole.

But because one of our parts is missing, you're going to need to subtract one part from the whole to help you get the missing whole.

So for example, two is the whole here, take away one, which is one of my parts, will give me my missing part.

So, two take away one is one.

Three take away two is one.

Four take away one is three.

Five take away two is three.

Four take away two is two.

Six take away three is three.

Well done if you've got all of those.

Let's have a look at the next ones.

I'm going to give you five seconds to solve the missing part.

Okay, let's go through them.

Seven take away one is six.

Eight take away two is six.

Three take away one is two.

Nine take away two is seven.

Six take away two is four and four take away three is one.

If I know that seven take away one is equal to six, then can I write one take away seven is equal to six? What do you think? You're right, I cannot do that.

I cannot change around my parts like that, because subtraction is not communicative.

We can not change around these parts and get the same answer.

Because unlike addition, when we subtract, it is not communicative.

Okay team, it is time for a spinner game.

And we are going to use our spinners now to help us come up with some equations that we can solve or some wholes and parts that we can solve, just like we've done with our number bonds within 10.

So I'm going to show you a quick clip now, that's telling you how to use it and then I'll explain to you what the spinner game is.

So watch carefully.

On the screen, you can see two images of spinner one and spinner two.

Now, you can see that I've drawn my spinners.

They're not perfect and that's fine.

So you can draw yours out yourself or ask a parent or carer to help you to do that.

Or remember there is a downloadable spinner that you can download from our resources.

Once you've got your spinner, you are going to need to take a paperclip like this one and place it in the centre of your spinner over where the lines cross.

And then in that gap, you are going to place your pencil or pen like I've done.

And you should notice that your paperclip can spin around that pencil.

So now you can flip that paper clip around and it will land on a number.

So that's going to be your spinner.

You can see from my two images that my spinner landed on the number seven on the first square over here, and two on the second square over here.

It's really important that you use this spinner first, with the digits five, six, seven, eight and this spinner second, one, two, three, four.

Brilliant.

Now that you know how to use your spinner, I'm going to ask you to pause the video now to get all of your spinner bits together so that you're ready to start the spinner game.

Remember to ask a parent or carer to help you with this task.

Fantastic, let's play the spinner game then.

So now that you'll spinners are all set up, the first thing you're going to do is spin the spinner on square one to get your whole.

Then you're going to spin the spinner on square two to get your first part.

And finally, you are going to use subtraction to identify what your second part is.

So if we think back to the video that I just showed you with my spinners, remember my first spinner land on seven and my second spinner lands on two.

So now I can use my sentences to help me work out what my second part is.

So my whole is seven.

My first part is two.

My first part is two.

Seven subtract two is equal to five.

My second part is five.

Okay.

Pause the video now to have a go at the spinner game and play when you are ready to continue.

In this half of the lesson team, we're going through looking at our number bonds within 20 now.

So we've just had a go at looking at our number bonds with 10, and now we're looking at these new number bonds.

So, I want you to have a look at the image of a village on my screen and the questions that are on the side of my screen.

So my questions are, how many flowers are there all together and how many orange flowers are there? So have a look for the flowers in my village scenes, they're all the way over here.

You might need to squint to see them a little bit, and I want you to tell me, how many flowers they were altogether and how many orange flowers there are? I'll give you a few seconds to count.

Brilliant, let's look at them then.

So there are 19 flowers altogether.

If I was to count all of those lovely flowers, I would know that there are 19 and there are nine orange flowers.

So nine of those flowers are orange.

A villager picks all of the orange flowers.

So a villager picks all nine orange flowers.

And we want to know now how many flowers are left.

But let's put this into a part-whole model.

So we know that our whole is 19.

19 is the number of flowers that there are altogether.

So those are our whole.

A villager picks nine.

So nine of them get taken away.

So we're going to partition our whole 19 now and move those nine into the first part.

You can see that we have 10 left.

So I know that my other part or my part that's missing is 10.

We could also have used our number facts within 10 for this.

So let's have a look at those.

If I know that nine take away nine is equal to zero, then I know that 19 take away nine is equal to 10.

What we saw with our part-whole model was that we had 19 as our whole.

We took away our first part nine and we were left with 10.

I could rewrite this equation as 19 take away 10 is equal to nine and this is why.

Because my whole is 19, so I started with 19, now one of our parts is 10, so I'm going to take away 10, like that and put it into my first part.

And you can see that I'm left with nine.

If I start with 19 and I take away 10 I'm left with nine.

We're going to use our number bonds within 10 to help us write equations here too and to work out some new number bonds within 20.

So for example, if I know that nine take away seven is equal to two, then I know that 19 take away seven is going to be equal to 12.

I also know if we think back to our last example with our 19 flowers, then 19 take away 12 will be equal to seven.

So I can switch around my parts.

If I keep my whole the same, I can switch around my part, seven and 12 and I can work out the other missing part.

Let's have a look at another one.

If I know this number bond within 10, eight to take away four is equal to four, then I also know that 18 take away four is equal to 14.

I can rewrite it like this, 18 take away 14 is equal to four.

Alright team, it is time for your independent task now and you're going to do exactly the same here.

So using your number bonds within 10, you are going to derive new number facts within 20.

So these are the number bonds within 10 and you're going to be working with.

And you're going to think about what number facts you can derive within 20.

I would like you to draw your tens and ones for each to check them.

I'm going to show you an example quickly and then I'm going to get you to pause the screen and have a go at yours.

So here's my example.

My number bond, oh sorry, my number within 10 is eight take away two equals six.

Because I know that eight take away two equals six, I also know that 18 take away two equals 16 or 18 take away 16 equals two.

Let's use our tens and ones to help show this or just to double check it.

So, I start off with my whole, which is 18.

And if I take away two of them, I should be left with 16.

So there's two in one of my parts, I'm left with 10, 11, 12, 13, 14, 15, 16, brilliant.

Now, let's take the next one.

18 is my whole.

And if I take away 16, I should be left with two.

There we go.

I've taken away 16 and I'm left with my other part two that I would move into here.

Brilliant, so now I've checked that, let's go back to the original independent task screen.

I would like you to use today your sentence starters, if I know then I know, which is at the bottom of the screen.

They're really useful sentence openers when we're comparing number facts.

Your challenge today is to see how many different ways, you can write your equations of your new derived facts.

So pause the video here to complete your task, resume once you are finished.

Great work team.

How many different ways did you write your equations? Well, let's have a look at just one example.

We're going to look at this bottom one.

Eight take away five equals three.

That number bonds to that number bond within 10 helps me to know some different number facts.

So let's look at them.

If I know that eight take away five is equal to three, then I know that 18 take away five is equal to 13 or 18 take away 13 is equal to five.

Well done on all of your hard work today team.

That is the end of our lesson now, but hopefully I will see you soon on another session, goodbye.

Okay guys, you know what to do.

So when the video has ended, don't forget to go and complete the quiz, just to remind yourself everything you've learned in today's lesson and recap your learning, good luck.

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