Lesson video

In progress...

Hello everybody, my name is Miss Hughes and welcome to today's session.

Today's lesson objective is going to be adding and subtracting ones from two digit numbers.

So let's get started.

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

So we're going to start by looking at adding ones to a two digit number.

Then you're going to have a talk task.

Next, you're going to have a go at subtracting ones to a two digit number.

And finally you'll have a main task and of course your quiz at the end to see everything that you have remembered from today's lesson.

In today's lesson, you are going to need a pencil and a rubber and sandpaper.

So please pause the video now to go and get these things if you have not got them already.

Brilliant.

To start us off into warm up brains up, we're going to have a look at some number bonds using subtraction.

So you can pause the video now and I would like you to answer each of the number bonds on the screen.

Off you go.

As we're going through the answers, I want you to have a think about a pattern.

Do you notice a pattern with the numbers and answers in our numbered bonds? So first one is three.

Four takeaway two is equal to two, three takeaway two is equal to one, two takeaway two is equal to zero.

Eight takeaway three is equal to five.

Seven takeaway three is equal to four, six take away three is equal to three, five takeaway three is equal to two.

Ten takeaway four is equal to six.

Nine takeaway four is equal to five, Eight take away four is equal to four, and seven take away four is equal to three.

Do you notice a pattern with those answers in our number bonds? if you look carefully at the whole that we started with, so our whole here 5,4,3,2,8,7,6,5,10,9,8,7, if we look at all of those individual columns, you'll notice that our whole is decreasing.

So our ten gets more to nine to eight to seven, eight decreases to seven to six to five, and because our whole is decreasing, and we're taking away the same part each time, so in this column two, in this column three, and this column four, our answer decreases.

So because our whole that we've started with decrease, our answers did too.

Well done if you spotted that pattern.

We're going to move on guys and we're going to look at this word problem on our board.

So I'm going to read it.

Fishermen went out to sea and caught 43 fish in an hour.

They caught four more fish in the next hour.

How many fish have they caught so far? Well, to workout this problem, I want to think what do I already know? Well, in this problem, I know the value of my parts.

I know that one part is worth 43 fish.

And my other part, as this 43 fish, sorry.

So that's four tens and three ones.

10, 20,30 40, 41, 42, 43, and my second part is four fish.

So I've got four in there like that.

I don't yet know what my whole is.

So I don't know how many fish we've caught so far, but I do know that in the first hour, they caught 43 fish and the second hour, they caught four fish.

I need to find out my total of fish by adding my two parts together.

So adding 43 and four together.

but let's add them all together and put them into the whole.

So that's 43 going into the whole and there's four going into the whole.

Brilliant.

Now I can add up what my whole is.

So my tenth remain the same.

I still got four tens, 10, 20, 30, 40.

All I need to do is add up my ones.

So 1,2,3,4,5,6,7.

So I've got 40 and seven which gives me 47.

So my whole is 47.

In total, they've caught 47 fish.

We're going to look at another way we could have solved that problem.

So what we were looking at was are two parts 43 and four.

We can partition 43 into two parts.

We can partition it into its tens.

So it's got four tens, which is worth 40, and three ones, which is worth three.

And we can use our known number fact and number bonds to help us solve this problem now.

So let's have a look at our ones then.

We know that 43 has three ones and we are adding four ones together.

I know that three add on four makes seven.

So we've got seven ones all together.

And so now I've got 40 and seven ones, which gives us 47.

So if I know that three, add four is equal to seven, then I'm able to know that 43 add four is equal to 47.

So that number bond, three and four equals seven helped me to know what 43 add four equals.

Let's look at this question now.

And look at this question at the top.

Which fact below helps me to calculate this equation? Well, we have three ones in 53 and five ones.

So we can use three add five to help us work out this problem.

If three add five equals eight, then 53 add five equals 58.

We can also partition 53 into tens and ones.

so five tens is 50 and three ones is three.

So now we need to add our ones together three and five, added together makes eight.

So if I know that three add five is equal to eight, and 53 add five equals 58.

Because after adding my ones together which is eight, I've got 50 and eight that I need to add together and 50 add eight is 58.

In your talk task today, you are going to do something similar.

You're going to be given an equation with a two digit number and adding ones.

And you need to decide which number fact helps you to work that out.

So let's take a look at this one quickly.

So I've got the ones two add seven.

That means that this number equation, two add seven is going to help me work out 32 add seven.

There we go.

I have highlighted it like that, because that's going to help us answer our equation.

So we can partition 32 into three tens which is 30 and two ones.

Now we can add our ones together.

So I know that to add seven is nine.

So now I've got to add my 30, all my three tens and then my nine ones.

So if I know that two add seven is equal to nine, then 32 add seven is equal to 39.

So we've used our number bond, two add seven is equal to nine to help us work out this equation.

So I'm going to ask you to pause the video now, to have a go at choosing which number bonds or number statements are going to help you to work out your equations.

Play the video when you're ready to continue.

Right team, let's go through those answers.

So the first one, six add three is going to help me work out my answer because I've got six ones and three ones.

Six ones add three ones is nine.

So 66 add three is going to be 69.

In this next one, five add two is going to help me because I've got five ones and two ones.

So 45 add two is going to be 47.

In this one, it's five add four.

This is going to help me because I've got five ones and four ones.

So 45 add four is 49.

Here, four add three is going to help me because I've got four ones add three ones.

So 54 add three is 57.

In this example at the bottom, 54 add five.

Four add five is going to help me because I've got four ones and five ones.

So 54 and five is 59.

And this one here 63 and four.

Three add four is going to help me because if I've got three ones and four ones equals seven, then 63 add four is going to be 67.

Brilliant.

Well done if you've got all of those.

We're going to have a think about subtracting ones now.

So let's have a look at our question.

Fishermen went out to sea and caught 47 fish, then they lost five fish off the side of the boat.

How many fish were left? Well, let's have a think about what we know already from this question.

So I know that our whole is 47.

So I've got 47 here as my whole because our fishermen caught 47 fish.

That was the whole amount that they started with sorry.

So let's double check.

We've got 47 here.

10, 20, 30, 40, 41, 42, 43, 44, 45, 46, 47.

So we know that our whole is 47.

We also know that they lost five fish off the side of the boat.

So we know that five of these fish went missing.

So one of my parts is five.

So let's put five of those in there.

There we go.

My first part is five.

That means that my other part is what's leftover.

So I'm left with 10, 20, 30, 40, 41, 42 fish.

So my other part was 42 and there were 42 fish left.

Let's look at another way that we could have solved this using our known facts.

We can partition 47 into four tens and seven ones.

Four tens is 40 and we've got seven ones there.

And now we need to subtract five ones.

So let's have a look at our ones now.

We've got seven ones, we can use on number fact seven, take away five, which is two to help us solve this problem.

So seven take away five is two.

So we're now left with four tens which is 40 and two.

So my final answer is 42.

If I know that seven takeaway five is equal to two, then 47 takeaway five is equal to 42.

Let's have a look at another example.

So we have the number problem.

Sorry yeah, the number problem 57 takeaway six.

And we want to know what our last part is.

So what known facts are going to help us to calculate this equation? I know that seven takeaway six is equal to one.

And this is going to help us work out this problem because if I was to partition my number 57, I have five tens which is 50 and seven ones.

So now I can do seven ones take away six ones, which leaves me with one.

So now I've got 50 and one which is 51.

So if I know that seven take away six is equal to one, then 57 takeaway six is equal to 51.

There we go, 51 is my answer.

So complete the equations on the sheets by using known facts to derive new facts.

When you've done the sheets or as you're going through, haven't look out for any patterns that you can spot in the numbers.

And let's go through these answers then.

And the answers were six takeaway four is two.

So we know that 16 takeaway four is 12 which helps us to know that 26 takeaway four is 22.

36 takeaway four is 32.

46 takeaway four is 42 56 takeaway four will be 52, and 66 takeaway four will be 62.

In this next one, we know that two add four is equal to six which helps us to know that 12 add four is going to be 16.

22 add four is going to be 26.

32 add four is going to be 36.

42 to add four is going to be 46.

52 add four is going to be 56 and 62 add four is going to be 66.

You might have noticed a few patterns from doing these questions.

So we can see that in each instance, we are taking away the same number of ones, and we have the same number of ones in our total number.

And that gives us the same number of ones in our answer.

So six ones take away four ones is equal to two ones.

And that's the same all the way through.

Same as two ones add four ones is equal to six ones.

So our ones have the same pattern across each of the equations.

You might have also noticed that in all of them, our tens do not change.

So 26 takeaway four, I still have 20 and two.

So still I got two tens there.

36 takeaway four is 32.

So I've got three tens here and I still have three tens here.

My tens have not changed.

Let's look at these answers now.

We know that seven or three is equal to seven take away four, which is going to help us answer the rest of our questions.

So 13 is equal to 17 takeaway four.

23 is equal to 27 take away four.

33 is equal to 37 take away four.

43 is equal to 47 take away four.

53 is equal to 57 take away four and 63 is equal to 67 take away four.

I'm not going to go through the last set of answers, you can see those ones yourself.

But notice again that my tens are not changing when I'm adding these one digit numbers.

And notice that there is a similar pattern between the number of ones that we are adding together and the number of ones that we are taking away.

That means that the number of ones and answer is the same.

So those are some of the patterns to spot.

Team, that is the end of our lesson for today.

So well done on your awesome hard work, and I look forward to seeing everything that you have remembered in your quiz.

Good luck.