Lesson video

Hello, everybody.

Welcome back to another mass lesson with me, Mrs. Pochciol.

As always, I'm hoping that we're gonna have lots of fun and also learn lots of new things.

So let's get started.

Today's lesson is called "Represent Addition and Subtraction Facts within 10", and it comes from the unit "Secure Fluency of Addition and Subtraction Facts Within 10".

By the end of this lesson, you should be able to represent addition and subtraction facts within 10.

Here are this lesson's key words, add, subtract, and represent.

Let's practise saying them.

My turn, add.

Your turn.

My turn, subtract.

Your turn.

My turn, represent.

Your turn.

Well done.

Now that we can say them, we can use them.

Here is the lesson outline.

So in the first part of our lesson, we are going to represent addition facts to 10.

And in the second part of our lesson, we are going to represent subtraction facts to 10.

So represent addition facts to 10, let's get started.

In this lesson, you are going to meet Izzy and Alex.

They're going to help us with our learning today.

"Izzy and Alex are playing an addition game with dice.

The children will throw two dice and find the sum of the two numbers.

Izzy rolls these numbers." Izzy's rolled a five and a four, so she's going to find the sum of five and four.

She writes an equation to show this.

Five plus four is equal to something.

Izzy's going to use her fingers to represent the parts five add four is equal to nine.

She has nine fingers up altogether, so five plus four must be equal to nine.

Well done, Izzy.

Let's have a go at this.

So "What are these fingers representing here? What would be the sum of the two numbers shown," A, B, and C? Can you find the sum and write the equation to match the representation? Come on back once you've had a go.

Okay, so let's see how you've got on.

A, three fingers and four fingers, so I know that this is representing three plus four.

I can see that there are seven fingers altogether, so three plus four must be equal to seven.

Well done if you've got that one.

Let's have a look at B, one finger and three fingers.

So I can see that this must be one plus three.

And there are four fingers altogether, so one plus three is equal to four.

And C, I can see that we have four fingers and four fingers.

And there are eight fingers all together, so this must be showing the equation four plus four is equal to eight.

Well done if you've got those correct.

It's Alex's turn now and he rolls these numbers.

Alex has rolled a three and a six, so he's going to find the sum of three and six.

What would his equation look like? Three plus six is equal to something.

Well done, Alex.

How are you gonna solve this? Alex is going to use a number frame to represent these parts.

Here's his number frame.

He's going to colour in three parts, and then six more parts, so that will show him the sum.

There we go.

So what is the sum of three and six, Alex? Alex can see that the sum is nine.

And he noticed that because one of the parts isn't coloured, so that means the sum is one less than 10, which is nine.

So three plus six is equal to nine.

Well done, Alex.

Some really good thinking there.

It's Izzy's turn to roll again.

And she rolls these numbers.

She's rolled a three and a four, so that means she's finding the sum of three and four.

Three plus four is equal to something.

Hmm, how are you gonna work this one out then, Izzy? She's going to use a number frame like Alex, but she's going to use it a little bit differently.

She's going to put three counters on the left and four counters on the right.

Let's see how she's going to work this out.

Izzy has noticed that this is a near double, so she knows that three plus three is equal to six.

But there's one more red counter, so that must mean the answer is seven.

Well done there, Izzy.

I love how you noticed that it was a near double using your old learning.

Alex now swaps Izzy's dice around and asks her what the sum will be now.

Izzy has not fallen for this trick because she knows that in addition, we can change the order of the addends and the sum will remain the same.

So let's swap our number frame.

So if we know that three plus four is equal to seven, then Izzy also knows that four plus three must also be equal to seven because all we've done is swap our amounts over.

So four plus three is equal to seven.

We can use this knowledge to quickly help us solve addition facts using our stem sentence, if I know, mmm, then I know, mmm.

Let's practise that, my turn.

If I know, mmm, then I know, mmm.

Your turn.

Remember to use that stem sentence throughout the rest of our learning.

Let's practise this idea.

So, "Which of these represent the same addends being added together?" So I'm going to show you a representation, and can you choose which number frame, A, B, or C, is showing me the same addends being added together? Hmm, what can we see here? One finger and four fingers.

Can you see a number frame that has the same addends? C, that's right.

Well done.

We can see that there is one red counter, which matches with my one finger, and four yellow counters, which matches with my four fingers.

But they have been swapped over.

Well done if you've got that one.

Oh, a number frame then, I can see here that we've got four yellow counters and two red counters.

Can you see a number frame that's showing the same addends being added together? B, that's right.

Well done.

Ooh, now this one, I've got half a number frame here.

What information can you see? And is that showing me the same addends as A, B or C? I can see four yellow counters and one red counter.

C is the answer.

I can see four yellow counters and one red counter.

But in C, they have been shown over the two sides of my number frame, whereas my representation only has one.

Well done if you got that one.

And finally, awesome dice.

Which of my number frames is representing the addends shown on my dice? I can see four and six.

A, well done.

That's right, but these addends have been swapped over.

First, I can see six yellow counters, and then I can see four red counters.

But the sum is still 10.

Well done if you've got those correct.

"Alex now rolls for his turn, but one dice falls onto the floor.

Izzy can see the other dice and says that the sum of Alex's dice is eight." So, "What number must be shown on Alex's second dice?" Alex can see that one of his dice is showing five.

And Izzy says that the sum of the two numbers is eight.

So how are you gonna work out what that missing dice is, Alex? He's going to represent it on a bar model to help him visualise.

We know that eight is the whole, as that is the sum of both numbers.

And he knows that he can see a five, so five must be a part.

The missing part is the dice that is missing.

So he can now see that five plus something is equal to eight.

He represents it using this equation.

Five plus something is equal to eight.

Hmm, how are you gonna work this out then, Alex? Alex uses what he knows to help him work out the other number on the dice.

He is remembered that this looks a little bit like a number frame.

He knows that five and three can be combined to make eight.

So three must be the missing number on the other dice.

Well done, Alex.

Some really good use of the knowledge that you already have there.

Right, let's explore this idea a little bit further.

"Alex and Izzy have now set you a challenge.

They have created this bar model to show the sum of two dice." But what could the dice look like that Izzy and Alex have thrown to find this sum? Record as many different ways that the dice may have fallen to find this sum.

Have a go and come on back to see how many of them you correctly found.

Okay, let's have a look at how many different ways we could have thrown those dice to find the sum of seven.

Our first one could have been a six and a one because we know that six plus one is equal to seven.

Izzy has given us a good clue there.

Remember that edition is commutative.

So if she knows that six and one is equal to seven, she also knows that one plus six is equal to seven.

So Izzy and Alex could have thrown a one and a six.

Well done if you got that one, or if you remembered that the rule of commutativity meant that you could swap those addends around and still get the same sum.

Let's have a look at another one.

You might have thrown a five and a two.

Well done if you got this one.

But remember, if I know five plus two is equal to seven, then we also know that two plus five is equal to seven.

So they could have thrown a two and a five.

Well done if you got that pair.

Izzy and Alex could have also thrown a four and a three because four plus three is equal to seven.

But remember, if we know that four plus three is equal to seven, they could have also thrown a three and a four.

Well done if you managed to find all of those different ways that they could have had the sum of seven.

Now, over to you.

For Task A, you are going to play your own version of Alex and Izzy's dice.

So you're going to, "Roll two dice and find the sum of the two numbers shown.

You could use a number frame to help you." Can you also please write the equation to represent what you have thrown? If you roll two sixes or a five and a six, just roll again as this is something that we will be exploring later on in your learning.

So go and have a go at this game, practise all of that addition, finding those sums, using those strategies, and come on back when you're ready to continue.

Welcome back.

I hope you enjoy playing Alex and Izzy's dice game.

Let's have a look.

So you may have done this.

Alex throws these dice.

He knows that it's six plus one is equal to something.

He knows that one more than six is seven.

Let's double check that on our number frame.

Well done, Alex.

Six plus one is equal to seven, well done.

So let's move on to the second part of our lesson, representing subtraction facts to 10.

Let's get started.

Izzy and Alex have now created a game to help them with their subtraction.

So they're now playing a card game.

"The children will turn over two cards and subtract the smaller number from the larger.

Alex goes first.

He turns over these cards," a six and a two.

Alex will now subtract two from six.

Six subtract two is equal to what? He's going to use his fingers to subtract two from six.

Wait a minute there, Alex.

Izzy's got a better idea.

She says that you don't need to use your fingers because she can see that six subtract two is just the even number before six, which is four.

She's used her knowledge, rather than her fingers.

Yes, Alex, it is much more efficient to do it that way, rather than use your fingers.

So well done, Izzy.

And well done, Alex.

"It's now Izzy's turn.

She turns over these cards," four and one.

Right then, Izzy, you are now going to calculate one minus four.

Hmm, remember Izzy, that in this game, we are subtracting the smaller number from the larger number.

So it will be four subtract one, not one subtract four.

Well done, Alex, a good spot there.

And well done, Izzy.

So four subtract one, how are you gonna work that one out, Izzy? When one is subtracted, we can see this as one less.

So one less than four is equal to three.

Four subtract one is equal to three.

Well done, Izzy, a very efficient method there.

Alex and Izzy now work together on this one.

And they placed two cards in a bar model.

So, "What equation is going to be represented?" They turn over of five and a two.

Hmm, what equation can we see here? Alex can see that five is the whole and two is a part.

So if we calculate five subtract two, it will give him the missing part.

Well done, Alex, that is the correct equation.

"How will Alex and Izzy now work out what the missing part is," though? What is five subtract two.

Alex is using some learning that he already knows.

So he knows that a part plus a part is equal to the whole.

Alex knows that two and three combine to make five.

So what does that mean for five subtract two? Hmm, if I know two plus three is equal to five, I know that five subtract two must be equal to three.

Well done, Alex, I love how you used what you already knew to help you to solve that subtraction.

Well done, Alex.

Now, "Alex has noticed that we can use our knowledge of addition facts to help us find subtraction facts." So let's use this bar model to help us.

We can see that five is the whole, three is a part, and two is a part.

So we can see that three plus two is equal to five.

Well done, Alex.

But if we know three plus two is equal to five, then we can swap the addends and say two plus three is equal to five because addition is commutative.

Now, can we see any subtractions in this bar model? If we know that three plus two is equal to five, we can also say that we know five subtract two is equal to three.

And if we know that two plus three is equal to five, we can say that five subtract three is equal to two.

This is a really useful tip because if you know your addition facts, you can then use that knowledge to help you to solve a subtraction fact.

So let's have a go at this.

"What number facts can we find using this bar model?" Can you find some addition facts, and then use those to help you find your subtraction facts? See if you can find all of the addition and subtraction facts related to this bar model, and come on back to see how you get on.

Okay, welcome back.

Let's see if you got them all.

So you may find these in a different order, but that does not matter as long as you found them.

One plus eight is equal to nine, that is an addition.

We know that addition is commutative, so we can swap our addends around.

So if I know one plus eight is equal to nine, we also know that eight plus one is equal to nine.

Let's see if we can find any subtractions.

So with a subtraction, we start with our whole.

So we know that it's nine.

If we subtract eight from the whole, I will be left with one.

So nine subtract eight is equal to one.

And if we know that eight plus one is equal to nine, we know that nine subtract one is equal to eight.

Well done, if you spotted all four of those equations.

Remember, we can use the relationship between addition and subtraction to help us to define different number facts.

Okay then, Task B, over to you again to play your own version of Alex and Izzy's digit card game.

"Turn over two cards and subtract the smaller amount from the larger amount to find the difference." Remember to write those equations and represent what you have done.

Remember to use what you already know to help you.

That is gonna be the most efficient way to find the difference.

Come on back once you've had a play of this game and are ready to continue.

Welcome back.

I hope you've had lots of fun playing our card game.

Let's see how Izzy got on.

Izzy turns over a nine and a three, so she's solving nine subtract three is equal to what? She's going to use a bead string to represent this.

Nine subtract three is equal to six.

Alex then confirms that she's correct by using his own method.

He knows that six plus three is equal to nine.

So nine subtract three must be equal to six.

Well done there, Alex, using what you already know to help you.

Well done for all of your hard work.

Remember, the games in today's lesson can really help you to practise and become more confident with your addition and subtraction facts, so maybe play these in your own time.

Let's have a look at what we've learned today.

Representing a problem can help us to find addition and subtraction facts.

In addition, we can change the order of the addends and the sum will remain the same.

We can use addition facts to help us to find subtraction facts.

So if I know that three plus two is equal to five, I know that five subtract two is equal to three.

You should be really proud of all the work that you've done today.

I've really enjoyed our mass learning today, and I can't wait to see you again soon.

Goodbye!.