# Lesson video

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Hey there? We all going to be up using on number bonds with 10 within 10, and applying them and using them for addition and subtraction.

So find somewhere quiet and peaceful to work and let's get started.

Here we have the equation 13, add 15.

Now here we have all deans representation as well.

Now, one of the strategies we could use is to count all so you can see here on my beads string.

I have 13 and this is 15.

I'm going to put them together.

I'm going to count all of the parts.

One, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28.

So we have 28 beads on my beads string.

Now it's your time.

So you are going to count to for 12 add 17 while we do it.

Great job.

Now with this strategy, what might go wrong? How quickly can you calculate with this strategy? Would it be a good strategy to use with 3-digits? This have a think tickle that greately matter.

Now with this strategy, you might miss count.

It's very time consuming.

Imagine doing that with 100 add, say 450.

We'll be here all day and we haven't got bead strings to solve them out.

Let's have a look at some other strategies that we might use.

Here we have 23 add 13.

So they're all my one scenes.

And I'm just going to get 23 add 13 on my beads string.

How we're going to have to count all of these and ones.

We ready.

You might have to help me.

One, two , three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 , 31, 32, 33, 34, 35, 36.

Oh my goodness.

I'm almost out of breath.

Well, now it's your turn for 37 add 12.

Pulls the while you count those out.

Brilliant.

Well done now with this, what might go wrong with this strategy? How quick you can calculate this strategy? Would it be a good strategy to use for 3-digit numbers? Have a quick think.

Just like the cancel strategy.

We might miss count and it takes a really long time.

Doesn't it? Is this going to be a very good gesture to use with 3-digit numbers? I'll let you think so.

So now we're going to count on in tens and ones.

Here We have 44, add 35, and I thought the Dean's representation is at the bottom so we can see we are going to count on our tens first.

So we have 10 , 20, 30, 40, 50, 60, 70.

So now we need to add on all ones 71, 72, 73, 74, 75, 76, 77, 78, 79.

That was much quicker this time.

Wasn't it? Now it's going to be your turn to count on add tens add one for the equation, 36 add 19 [foreign Language] while you do it.

Great job with.

What might go wrong with this strategy? Can we quickly check ? Can we quickly do this? Would it be a good strategy for 3-digit? So this one, again we do have to have very careful not to mix up our tens and ones, or we might even forget our tens.

So we have to be really careful.

We can quickly count with this one much better than the other two, but it's not the fastest way.

And this, this is going to be a good strategy for three digit numbers.

What do you think? It might be a little bit hard.

Especially when you've got to keep hundreds, tens out ones in your brain.

Let's do some exploring.

So here we have 57 subtract 34, is equal to something.

So we're going to use one of our strategies to calculate the tens and to calculate the ones.

Now I get to be a bit sneaky.

I'm going to use my number, bond knowledge.

What are we going to use? Number bond knowledge.

So I'm going to look at my tens best so I can see I have five tens and 57 and three tens is that you full say five tens take away three tens is equal to two tens.

To calculate the ones I'm going to do exactly the same.

And seven subtract four is equal to three.

That fully answer is two tens and three ones.

Wait a second.

That's not how we say we say it What's the answer? Well done.

It is 23.

So now it's your 10 stupid exploring.

He had four different equations and I've given you the two sentence stuff is that I used to calculate.

The tens are used and to calculate the ones I used.

So good luck,.

Great job.

Let's keep going with our learning to here.

We have, a subtraction equation.

65 subtract 42 is equal to ,well it's equal to something.

And here we have two facts.

Six is equal to four and two and five is equal to three, two, but how could these two addition facts help us to solve the subtraction equation? What do we know about addition and subtraction? we know that they are the inverse operations.

So we know that six is equal to four add two, but we also know that six subtract four is going to be equal to two.

Likewise for five is equal to three add two.

We know that five subtract two is going to, Two is going to be equal to three.

So let's have a think.

Six subtract four is going to be two.

So we know it's going to be 20 something, and five subtract two is equal to three.

So the answer is 23.

Your independent task, you are going to be using your number bond knowledge with intent to solve these onsets.

We have 66 add 22 is equal to something.

94 subtract 73 is equal to something, 67 subtract 35 is equal to something.

And 24 at 65 is equal to something.

Fit.

Each of these calculations you need to make sure you have written a sentence expense to how you calculated the tens and how you calculate the ones.

Amendments or pools the VTA before writing your answer.

Well done everybody.

Now it's time to take and fix our independent task.

Here on the screen, you can see the four different equations with that onsets.

Say 66 add 22 is equal to 88.

94 subtract 73 is equal to 21.

67 subtract 35 is equal to 32.

24 add 65 is equal to 89.

For each of these to calculate the tens.

I partitioned each sum.

For example, the first sum becomes six add two is equal to eight.

So if I know that, then I know that 60 add 20 is equal to 80.

To calculate the ones I simply used.

Six add two is equal to eight for the second sum to calculate the tens I used.

If I know that nine take away seven is equal to two, then I know 90 subtract 70 is equal 20.

To calculate the ones are useful ,Take away three, which is equal to one.

For the third sum to calculate.

The tens are used.

If I know that six subtract three is equal to three, then I know that 60 subtract 30 is equal to 30.

And to calculate the ones I use seven subtract five, which is equal to two.

For the final sum to calculate the tens are used.

If I know that to add six is equal to eight, then I know that 20 add 60 is equal to 80.

And to calculate the ones I use for add five is equal to nine.

Well done everybody.

If you'd like to please ask your parent or care to share your work on Twitter, tagging @national and hashtag #Learnwithoak.

Well done for some great learning today.

And don't forget to take the quiz.

Take care.

Bye.