# Lesson video

In progress...

Hello mathematicians, how are we all feeling today? I am feeling very excited about our math lesson and Hedwig is here with me ready to be my talk partner.

Should we find out what we're going to do today? So today we are going to identify one more, and one less than a number within 20.

We're going to explore one more and one less on a number line, and we'll represent one more and one less in lots of different ways, then you will do your independent task and your end of lesson quiz.

Today you're going to need a pencil and some paper, let's get started with the brain teaser to warm our brains up shall we? Now have a look at the cubes in front of you, we need to know which numbers are represented.

What's the same and what's different.

So look carefully, let's count the blue ones.

I'm going to count them and tell Hedwig what I can count, maybe you can tell your talk partner as well, let's count carefully.

Six, six cubes, six cubes, and six cubes, and then that one's got one more.

What did you talk to your talk partner about? We counted together and we counted that both of those stacks of cubes have six blue cubes, and then the first stack has one more yellow blue cube, one more than six is seven.

The blue part is the same, the yellow part is different, seven and six have a difference of one.

Can you see the difference of one there? There's one more cube, right.

Now that we're all warmed up let's go through our star words, get your hands ready, hands up star words.

One more, one less, difference, tens, ones.

We'll need to use those words today when we're explaining the numbers.

So let's have a little bit more of an explore using the same idea.

Which numbers are represented? Well, I can see that I've got a group of ten, one, two, three, four, five, six, seven, eight, nine, 10.

Both of those stacks have a group of 10, those are the yellow cubes.

Now what is different about them? Well I can see that there are two grey cubes, 10 and two more is equal to 12, and then the next stack has 10 and three red cubes, 10 and three more is equal to 13.

I've increased by one, one more than 12 is 13.

So what would come next? Have a think? 12, 13, can you shout it out? Shout out at me what comes after 13? 14, let's have a look.

A group of 10 and four more.

The numbers have increased by one each time.

10 and four more is equal to 14.

So what would come after that then? Shall we yell it to the screen again, are you ready? Tell me what comes after 14? 15, well done.

A group of 10 and five more, 10 plus five is equal to 15.

So then what would come before the grey ones? This is a little bit trickier because we've been increasing each time adding one more, but what if I wanted to know what comes before? Well I can see that there are two cubes and then three extra cubes, and then four and then five extra, so I know that I need to decrease.

What's one less than two? One less than two is equal to one, so I've got a stack of 10, a group of 10 and one more, 10 and one more is equal to 11.

So we've increased by one each time, 11, 12, 13, 14, 15.

Let's have a look at this on a number line.

Which number is one less than 12.

Now let's have a think, if it's one less, I know my numbers are getting smaller, they are decreasing, so I need to go down the number line towards the zero, So let's all find the number 12, can everyone point to the number 12, put your finger on that, on the number line, one less than 12.

One less means one jump, everybody do one jump, one less than 12 is equal to 11.

11 is one less than 12.

Now let's have a think, what is one more than 19? Oh, one more this time not one less.

If I am adding more it means the numbers are increasing, they're getting bigger, so I need to move up the number line towards the number 20.

What is one more than 19? Everyone put your finger on number 19, can you point to it, one more, let's all do one jump are you ready? One more than 19 is equal to shout out at me, 20 well done, let's say that with a full sentence.

One more than 19 is 20, lovely mathematical language everybody.

Now, you are going to practise doing this straight on with your independent task, but because the independent task is quite tricky, I'm going to take you through it very, very carefully.

I'm going to give you a target number, and then you are going to find one less and one more than that target number, so let's look carefully together.

This looks a bit tricky doesn't it? I've got a row here that I need to complete, and row here.

And when you get your version, you'll have all of the boxes missing, with the numbers missing.

Let's look carefully at this one first.

The first thing that we need to look at is the number in the middle, the main number, that one, can everyone point to that? That target number here is number one.

There is one cube, the word one, and the digit one.

Once you've identified that number, you need to find one less than one.

So one less than one, if I have one, one less than one is zero, so I would draw no cubes, I'd write the word zero and draw the digit zero.

Once you've identified one less, you need to identify one more than one.

So I think of my target number one, one more than one, you can use the number line to help you, one more than one, if I add one more, it's equal to two.

So I've drawn two cubes, I've written the word two and I've draw the number two.

Then you can have a look at it on the number line.

So here's my target number one, I've started off on the number one, one less than one, one jump that gets me to zero, and one more than one, that is equal to two.

So I've shown my number, I've written one less, one more, and I've shown it on the number line.

Should we try again, just to be double sure, are you ready? Let's try this one.

What's the first thing that I look at? I need to look at the target number, there's my target number.

What is my target number? Look very carefully, it's 11.

The target number is 11, let's double check.

There's a group of 10 and one more, 10, 11, there are 11 cubes, that's the target number and I've written the word 11 and I've drawn 11 as a digit in the box.

Once you've identified that main number, you can find one less.

I'm going to look on my number line to help me.

Number 11, what's one less than 11, one jump less than 11 is equal to 10.

So I draw 10 cubes, I write the word 10 and I write the digit 10 in the box.

Then we can identify one more, one more than 11, find 11 on the number line, everyone do one more, one jump, one more than 11 is 12.

So I can draw a 12 cubes, a group of 10 and two more is equal to 12, I can write the word 12, and I can write the word, and I can write the digit 12 in the box as well, then you can show it on the number line.

Start at 11 that's your target number, one less than 11 is 10, and one more than 11 is 12, there it is.

Now it's your turn, look carefully.

The first thing that you do is identify the target number, so look for the target number, how many cubes are in that box? One, two, three, four, five, five, so your target number is five, you write the word five, and draw the digit five as well, and then you can find one less and one more.

Once you've done that come on back and we'll check the answers together.

Is a little bit tricky, so make sure you take your time and go really, really carefully and use the number line to you as well.

Off you go, have a go now.

How did everybody get on? Let's go through them together.

So the first one you're target number was five, one less than five is four, on your number line one jump is four.

So draw four cubes, write the number four and the digit four.

Then I need to find one more than five.

One more than five is six, one jump up the number line six, then underneath your target number was 15, can you see that group of 10 and five more is 15, write the number 15 and write the digits 15.

And you can use the number line to help you find the 15, then we need to find one less than 15.

One jump, one less than 15 is equal to 14.

Then we need to find one more than 15.

That's one jump up the number line because it's more, it's increasing.

One more than 15 is 16, so you draw a 16 cubes, write the word 16 and the digit 16 as well.

You have done an absolutely fantastic job with that.

That was a tricky activity to do.

Should we wake Hedwig up and explain to her what we did? Say wakey-wakey, Hedwig, wakey-wakey.

We had a lot of fun exploring with that puzzle today, we have to fill in lots of missing boxes.

Now what did we do throughout this lesson? Well the aim of the lesson was to identify one more and one less, so we had to think about what that meant.

One more means that the numbers are increasing they're getting bigger, so we go up the number line and one less means that we're going down the number line because we're taking them away, the numbers are getting smaller.

And then we use a target number to find one more and one less than that target number, and we went and really, we did some really great work with representing it with cubes, and also writing the word and writing it in digits as well, so we represented it in loads of different ways, do you think you understand that? I think that, I think that she really understood that lesson I hope that you did too, and you're ready to explore in the next one.

Off you go and I've got your quiz now and I'll see you very soon, bye.