Lesson video

Hello everyone and welcome to Maths with Ms. Dobrowolski.

Today, We'll be using the "Make Ten" strategy to subtract the one.

So let's have a look at our lesson agenda.

First, we'll be looking at when can we "Make Ten"? And then we'll be having our talk task, followed by looking at two-digit numbers and the "Make Ten" strategy, and then you'll be off your independence task.

For this lesson you will only need a pencil and notebook.

If you don't have these items, that's okay.

Pause the video now and go get them.

Super.

Let's move on.

So when can we make a 10? When is the "Make Ten" strategy actually useful for us? Well, let's take a look at the three equations I've put up on the slide.

So, first off I have 14 minus three.

Mmh, 14 minus three.

Well, I can just use my known facts to help me figure this one out.

Four minus three is equal to one.

So that must mean 14 minus three is equal to 11.

Same with 14 minus four.

What known fact can help you here? Have a think? Hmm? Oh, I know four minus four is equal to zero.

So 14 minus four must be equal to 10.

What about 14 minus five? Four minus five, well, that's not a known fact, so I don't really have a known factor that will help me.

What other strategy can I use? Well, first I thought, okay, I can just count backwards from 14.

14, 13, 12, 11, 10, nine, but, I can also use the "Make Ten" strategy.

And here, let's take a look at how I do that.

So 14 is my whole.

I know that 14 is my whole, because that's the number I'm subtracting from.

I know that 14 minus four is equal to 10.

So that means I can partition five into four and one.

So 14 minus four is equal to 10.

Then 14 minus five is equal to nine because I've only taken away one less.

It is one less.

One, two, three, four, five, six, seven, eight, nine.

So I took away four.

I subtracted four and I subtracted one.

So it's one less than 10.

So 14 takeaway away five is equal to 14 minus four minus one.

Both of these equations are equal because five has been partitioned into four and one, which is equal to nine.

Let's have a look at 14 minus six.

So again, 14 is my whole.

10 plus four is 14.

14 is my whole, because that's the number I'll be subtracting from.

So, again, I know 14 minus four is equal to 10.

So that's me using my "Make Ten" strategy.

So, that means I can partition six into four and two.

Four plus two is equal to six.

So, if I know 14 minus four is equal to 10, then 10.

Then 14 minus six must be equal to eight because it is two less.

One, two, three, four, five, six, seven, eight.

So you see the six has been partitioned and I've taken away four, and then I've taken away another two.

So that means 14 minus six is equal to 14 minus four minus two.

And both of these equations are equal because six has been partitioned into four and two to help me make a 10.

So these equations are equal.

Let's have a look at these three equations.

Do I need to "Make Ten" strategy to solve all of them? Well, 10 minus five, I know my number bonds to 10.

So I know 10 minus five is equal to five.

I don't need the "Make Ten" strategy here because I'm not crossing a 10.

What about 11 minus five? Hmm? Well, I know 11 minus one is equal to 10.

So yeah, I couldn't use the "Make Ten" strategy here.

11 minus one is equal to 10.

So I can partition the five into one and four.

So, here's my 11.

That's my whole because that's number I'm starting with.

11 minus one is equal to 10, and 10 minus one, two, three, four leaves me with six.

So here we had minus one and minus four.

11 minus five is equal to six.

Now let's try 12 minus five.

Do I need to use the "Make Ten" strategy? Well, I know 12 minus two is equal to 10.

So yeah, I could use the "Make Ten" strategy.

So if 12 minus two is equal to 10, that means I have to partition the five into two and three.

So 12 minus two is equal to 10, and 10 minus one, two, three, leaves me with seven.

So, minus two, minus three is equal to seven.

Wow, already time for our top task.

For this top task, I'd like you to figure out, do you need the "Make Ten" strategy? So remember, we have the Say this box here because we need to be using mathematical language.

So, as always, I'll do one example and then you're off on your own.

So, I have 16 minus five here.

I have the equation 16 minus five.

I think we do not need the "Make Ten" strategy because I have a known fact here.

Six minus five is equal to one.

So 16 minus five must be equal to 11.

So you don't need to "Make Ten" strategy.

So remember you only use the "Make Ten" strategy where you partition the second number.

You only need that when you're crossing a 10.

And here, 16 minus five was equal to 11.

So, pause the video, finish your top task, and resume when you're ready so we can go over the answers.

Great, so let's see.

Did you need the "Make Ten" strategy for all of them? For 12 minus five, yes you did.

Because there was no known fact here.

12 minus two is equal to 10 and then 10 minus three was equal to seven.

For 16 minus five we already said no.

11 minus four yes, you did.

11 minus one is equal to 10, and 10 minus three is equal to seven.

14 minus four, no, you did not.

Because 14 minus four is equal to 10.

17 minus six, no, you did not.

You could use your non-fact.

Seven minus six is equal to one.

So 17 minus six must be equal to 11.

13 minus six, yes, you did need to make a 10.

13 minus three is equal to 10, and 10 minus three is equal to seven.

14 minus three did not need a "Make Ten" strategy.

Four minus three is equal to one.

So 14 minus three is equal to 11.

And 11 minus three, yes, you did need to "Make Ten".

11 minus one is equal to 10, and 10 minus two is equal to eight.

Well done everyone.

So, let's look at using two-digit numbers and the "Make Ten" strategy.

And I'll use my number line to help me here.

So, I can use a number line here to help me.

Let's have a look at 11 minus four.

So how can we use the "Make Ten" strategy here to help us? Well, I know 11 minus one is equal to 10.

So I can partition the four into one and three.

One plus three is equal to four.

So, I would partition four into one and three which means, 11 minus one is equal to 10.

And then 10 minus one, two, three is equal to seven.

So 11 minus four must be equal to 11 minus three, minus one.

Both sides of the equation are correct, are equal, because four has been partitioned into one and three.

Let's keep going.

Let's have a look at 21 minus four.

Well, I know that 21 minus one is equal to 20.

So I can partition the four into one and three.

So 21 minus one is equal to 20.

20 minus three.

Count with me.

One, two, three, is equal to 17.

So 21 minus four is equal to 21 minus one minus three.

Let's have a look at some more examples.

So here I have 12 minus five.

When I counted backwards, I know that 12 minus five is equal to seven.

12, 11, 10, nine, eight, seven.

However, we could also solve this by using the "Make Ten" strategy.

I know 12 minus two is equal to 10.

So that means I'm going to partition the five into two and three.

So, 12 minus two, one, two is equal to 10.

And then 10 minus three, one, two, three, is equal to seven.

Now, what I can do, is I can check my answers by doing the inverse or the opposite.

So if 12 minus five is equal to seven, then the opposite must be true.

Seven plus five must be equal to 12.

Well, let's think.

Remember, five can be partitioned into two and three.

So seven, let's jump forward three.

One, two, three, and then jump another two, one, two.

Oh good! Seven plus five is equal to 12.

So I know my answers are correct.

Let's try another example.

22 minus five.

Again, we can use the "Make Ten" strategy to help us.

If I'm starting at 22, mm? What 10 can I make? Oh, I know.

22 minus two is equal to 20.

So I can partition the five into two and three.

So we start at 22 and we take away two, jump two.

We also have to make sure we jump another three.

One, two, three.

So that will land me here at 17.

So 22 minus five is equal to 17.

Now, I'm going to check my answer by doing the inverse or the opposite.

If 22 minus five is equal to 17, that means the opposite must be true.

17 plus five should be equal to 22.

But let's count up and check.

So we need to count up by five.

17 is our beginning number.

One, two, three, four, five, and we land on 22.

So yes we are correct.

Let's try one more.

32 minus five.

What 10 can we make here? Well, I know 32 minus two is equal to 30.

So that means we can partition the five again into two and three.

So we start at 32 and we take away two, one, two.

We're at 30.

And then we have two minus another three.

One, two, three.

That takes us to 27.

So that means 32 minus five is equal to 27.

Now, again, I'm going to check my answer by doing the inverse or the opposite.

27 plus five should be equal to 32, but let's count up and check.

So we start at 27 and we count up five.

One, two, three, four, five.

Excellent, we land at 32.

So now I know that I was correct.

Let's look at a few more examples.

So, for example, I have 23 minus six.

Let's use the "Make Ten" strategy to help us.

Oh, I know 23 minus three is equal to 20.

So, I can partition six into three and three.

So I know that.

Mm, 23 minus three, one, two, three, is equal to 20.

And then I need to subtract another three.

One, two, three.

That will take me to 17.

So 23 minus six is equal to 17.

I'm going to check my work by doing the inverse or the opposite.

So 17 plus six should equal 23.

But let's count up and see if we're correct.

So we start at 17 and we count up six.

One, two, three, four, five, six.

Excellent, I was correct.

17 plus six is equal to 23.

So 23 minus six is equal to 17 was correct.

33 minus six.

Hmm? Well, I know that 33 minus three is equal to 30.

So partition the six into three and three.

So, 33, first we have to subtract three.

One, two, three.

That takes me to 30.

And let's subtract another three.

One, two, three.

That takes me to 27.

So 33 minus six is equal to 27.

But I want to check my work with the inverse or the opposite.

So that means 27 plus six should be equal to 33.

But let's check.

We'll start at 27 and count up six.

One, two, three, four.

Oop, sorry about that.

So we start at 27 and count up six.

One, two, three, four, five, six.

And yes, that is equal to 33.

So I know my answer is correct.

And it's already time for your independent tasks.

So as usual, I'll do one and then you'll be off on your own.

So for this independent task, there's two steps.

Step one, is to use the "Make Ten" strategy to solve each equation, and you can use the number line to help you.

So I did 12 minus seven.

I know 12 minus two is equal to 10.

So I partitioned the five into two and three.

12 minus two is equal to 10, and 10 minus three is equal to seven.

Excellent.

So now step two, is the inverse to check your work.

So if 12 minus five is equal to seven, then hopefully seven plus five will be equal to 12.

So I start at seven and I count up five.

One, two, three, four, five, excellent.

Seven plus five is equal to 12.

Your turn, when you're ready.

Pause the video and resume when you're finished.

See you when you're done for the answers.

Excellent, so let's take a look.

22 minus five was equal to 17.

And I knew that was correct because I did the inverse.

32 minus five was equal to 27.

42 minus five was equal to 37.

32 minus four was equal to 28.

32 minus five was equal to 27.

32 minus six was equal to 26.

And 32 minus seven was equal to 25.

Well done everyone.

That was quite a lot of work.

If you'd like to, you can share your work with Oak National by asking your parent or carer to share your work on Instagram, Facebook, or Twitter, tagging @OakNational and a #LearnwithOak.

As always, don't forget to complete your final quiz.

And I really hope to see you next time, bye.