# Lesson video

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Hello, everybody, and welcome to today's session.

My name is Miss Hughes and in today's lesson, we're going to be exploring some mental strategies that we can use to add three one-digit numbers together.

So, let's get started.

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

So, we're going to begin by exploring strategies that are going to help us calculate addition sums in our head.

Next, we're going to have a bit of a let's explore task, where you're going to have a go at this yourself in a bit of a puzzle.

Then, you're going to be choosing and explaining strategies that are helping you to do addition sums in your head.

And lastly, we have a main task and of course your quiz at the end of the lesson.

For our today's session, you are going to need a pencil and rubber and you will also need some paper.

So, pause the video here to get those things if you have not got them with you already.

Brilliant, let's move along.

So we're going to start off today's lesson with a bit of a brain warmup.

And I want you to think about what these numbers are represented as words.

So you can pause the video here to have a go at writing all of these numbers out into words.

Remembering the spellings, off you go.

Let's have a look at some of these answers then.

So, 11, 22, 33, 44 and 55 were the numbers that are on our board and they are represented in words like.

Our next set of numbers are 66, 77, 88 and 99, and we represent those numbers in words like this.

Well done, if you've got some of those tricky spellings especially 44, I think it's really important to remember that there is not a U in the word forty.

Okay then, so for this first start of our lesson, remember, we're going to be exploring some strategies that are going to help us with addition sums in our head.

So I want you to have a little look at the ducks that I have on my board.

I've got four ducks in the middle that are in the pond, there are three ducks on the left hand side of my pond.

And there are six ducks on the right hand side of my pond.

And I want to know how many ducks that are all together.

Let's put this into a pothole model.

So this is my pothole model, I know I've got the value of these three parts because I know my three values of ducks.

I've got a three, four, and a six.

What I don't know is my whole, yet.

I don't know how much or how many ducks I have all together.

To work that out, I'm going to add all of my parts together.

So, my equation for that would look like this.

Three, add four, add six is equal to our unknown whole.

So we're adding all of our parts together to find that unknown value.

There are a few strategies that we could use in our head that would help us to work this out quickly.

We could use a number bond to 10 strategy to work out this calculation in our heads or make it easier for ourselves at least.

So, three, add four, add six, straightaway, I can see there's a number bond to 10 in there.

Have you spotted it? Brilliant, it's four add six.

I need that four, add six, straightaway you make 10.

So I can write that as an equation four add six, equal to 10 We can see that in a 10s frame as well and counters to represent it.

So, here's the 10s, here are two 10s frames and in my top 10s frame, let's say I've got four counters, I can see I just need six left to make 10.

I've got six in my equation, let's add them.

Now that we've got 10, I know that all we've got left to add is our three.

I know that 10 add three is 13.

We can represent that in our 10s frame as well.

That was using number bonds to 10 to help us work with our equation.

We could have done it in another way.

We could have used a near doubles strategy.

I'm going to explain that now.

And let's look at the first part of my equation.

I've got three add four.

When I'm adding four to the number three, it's a bit like doubling three and adding one.

Three doubled is six, add on one is seven.

So, it's like this.

Three add four, is the same as saying three doubled, add on one, which is seven, and I can represent that in my 10s frame now.

Three, doubled is six, add on one is seven.

Now, all I need to do is add on my six.

Seven add six is thirteen and I can represent that in my 10s frames.

Let's have a look at another one.

So let's try and use our number bonds to 10 again, to answer this equation, six, add seven, add three.

Straightaway, I can see a number bond to 10.

Have you got it? Brilliant, it's seven, add three.

Seven, add three equals ten And we can represent that in a 10s frame like this.

I've got my seven counters and three counters, which make up my 10s frame.

And now all I need to do is add on six, which gives me 16; 10 add six equals 16 Let's have a look at the near double strategy.

Can you see a near double in this equation? Well done, it's six add seven.

That is a near double.

I know that a number bond that I can use to get a seven, is six add one.

So, six add seven is a bit like saying double six and add on one, like this.

So, we can double six to make 12, add on one makes 13, and I can represent that in my 10s frame like this.

Double six, it makes 12.

And now all I need to add on is three, and I know that 13 add on three is 16.

Okay team, it's the time for our let's explore task.

So, I would like you to put into practise our number bond to 10 strategy, and our near double strategy to help you with this task in your head.

You have been given five digit cards, four, five, six, seven and eight.

What you need to do is arrange the cards in this grid, so that the total number of the three numbers in a straight line, so the straight line vertically, up and down, and horizontally, across, is always the same.

So, pause the video now to have a go at this task and play the video when you're ready to continue.

Good luck! Okay, team, it's time to have a look at these now.

I'm really intrigued to see how you got on with this one.

So, let's have a look at my example.

Now, there were a number of different ways that you could have worked this out.

This is the way that I did it.

So, well done if you did it this way.

But remember, if you did it another way and it still works out, then fantastic.

That's great, you found a new way of doing it.

We're going to explain how this one works though.

If I put four, the digit card four in the middle and arrange my other cards around like this, then I'm able to make my vertical line make the total 17 and my horizontal line will be 17.

So, if five, add four, add eight, will be 17 and six, add four, add seven, will be 17.

I'm going to use my number bonds to 10 to check my vertical line.

So, straightaway, I can see that six and four is number bond to 10.

I know that six add four is 10.

If six and four makes 10, then all I need to do now is add on seven.

And I know that 10 add seven makes 17.

So, here are the equations I was doing in my head.

Six add four is 10, 10 add seven is 17.

I can't see a number bond to 10 in my horizontal line, but I can see a near double here with five and four.

So, I'm going to use my near doubles technique to check this line.

I want to add five and four in my head and I know that four doubled makes eight, add on one, makes nine.

So, I know that four add five is nine because five, remember, can be made from four and one.

Now, that I got nine, all I need to do is add on eight.

So, I know that my whole number is 17.

So here are my equations showing that.

Five add four is nine, and I know that five is the same as saying four add one.

So, I've doubled four and added one to get nine.

Okay, team, so now that we've looked at our answers, we're going to have a think about explaining the strategies that we have used.

And to do that, we're going to use these sentence starters.

The top one is, firstly, I used the strategy, and the next one is, then, I used the strategy.

So let's have a think about how we can explain the strategies we used to mentally calculate this vertical line and check whether it added up to the same number or add up to 17.

So, I would start off by saying, first, I used the strategy of number bonds to 10.

I added six and four which makes 10.

Then, I used my number bonds within 20 to make 17.

So, I added 10 and seven to get 17.

Now that I've explained that row, I can use these sentence starters to explain second row.

Firstly, I used the strategy of near doubles to add five and four together.

I did four doubled, which is eight, and then added on a one, which made the total nine.

Then I could use my number bonds within 20 to add nine and eight together, which was 17.

I would like you now to have a go at explaining the strategies that you used to figure out or to check your explore task.

Okay, so pause the video now to have a go yourself at explaining the strategies that you used to check your answers and to check that each of the cards that you put in place make the same total, and press play when you're ready to continue.

Okay, it's now time for the independent task, guys.

So, you have been given a number of equations that you are going to need to solve, and they are similar to the equations that we've seen throughout today's lesson, where you are adding three one-digit numbers.

What I want you to do is think carefully about the strategies that you can use.

The ones that we've learned today are number bonds to 10 and our near doubles, that you can use to solve these problems. A big part of today's task is being able to explain which strategies you use to solve the problem.

So have a think about how you're going to explain it in words, on your sheet of paper.

If you need to, or if you would like to, there are some 10s frames that you can print off from our downloadable resources, if that is going to help you to solve the equations and to see it pictorially with counters, you can do that.

Pause the video now to complete your task and resume the video once you are finished.

And let's go through those answers.

So, the first equation was six, add three, add four.

Now, there were a few strategies you could have used.

I personally used number bonds to 10 because I could see that six add four make 10 and then I could add 10 and three together to get 13.

You may have also used near doubles and strategy because three add four is the same as three doubled, which is six, add on one, which is seven.

And then you could have added seven and six together to get 13.

The next one, eight add two, add seven, is equal to 17.

I used the number bonds to 10, so I knew that eight add two make 10 and then I could add on seven to 10 to make 17.

You may have used near doubles again because eight add seven is a near double.

Seven doubled is 14, add on one is 15.

And then I just need to add on two, which makes 17.

Let's look at the next one, four, add five, add three, you could have used the near doubles again, here, because four add five is the same as saying four doubled, which is eight, add on one, which is nine.

And then we could use our number bonds within 20 to work out nine add three, which is 12.

Finally, five, add four, add six, is 15.

I used my number bonds to 10 again for this one because four add six is equal to 10, add on the five, is 15.

Well done, if you've got the answers to those equations and used some of those strategies.

Team, well done on your fantastic hard work today with thinking of those mental strategies that you could use to add three single-digit numbers.

Good luck on your quiz and hopefully see you in another session soon.

Bye-bye.

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

Now, all that's left for you to do guys is complete the quiz So, when the video is finished don't forget to do that.

I'm going to be excited to see everything that you've remembered or taken away from today's lesson.

Good luck!.