# Lesson video

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Hi and welcome back to your math lessons.

We are looking at number sense today, and we're going to be deriving new number facts from number bonds.

I can't wait to get learning with you today.

So make sure you have all the things that you need and that you're in a nice, quiet place ready to learn.

Here is our lesson agenda for today.

As you can see, we're going to be starting off what do we already know about addition and subtraction before moving on to deriving number facts, and then moving on to our independent task and quiz.

Before we start, make sure you have a pencil, paper and ruler in front of you.

What do you already know about addition and subtraction? Well, we know the commutativity for addition, for example, we can move around the numbers in the equation, they'll still equal the same thing.

We might have three add one is equal to four and one add three is equal to four.

We have all inverse relationships.

We know that addition and subtraction are opposite operations.

Therefore, they are the inverse of each other.

And we also know that additional and subtraction are made of parts and wholes.

If I know that four add seven is equal to 11, what else do I know? Pause the video and take all that grey matter.

Let's have a look together.

If I know that four add seven is equal to 11, then I also know that seven add four is equal to 11 because we know that addition is commutative.

If I know that four add seven is equal to 11, then I know that five add seven will be equal to 12.

If I know that four add seven is equal to 11, then I know that 40 add 70 is equal to 110.

If I know that four add seven is equal to 11, then I know 14 add seven is equal to 21.

If I know that four add seven is equal to 11, then I know that 11 subtract four will be equal to seven.

If I know four add seven is equal to 11, then I know that three add seven is equal to 10.

If I know that nine subtract three is equal to six, what else do I know? Now a top tip here is to make sure that you remember to use your commutativity, place value and the inverse.

Pause the video and write what you know.

Well done, lets go through this one together.

So we have nice subtract three is equal to six, therefore, eight subtract three is equal to five.

We will have 90 subtract 30 is equal to 60, 19 Subtract three is equal to 16.

We'll also have six add three is equal nine and eight subtract three is equal to five.

So now it's your turn, you're going to have the equation, four add nine is equal to 13 and you're going to use these subheadings to derive as many number of facts as possible.

So pause this video and write down your answer.

Brilliant, let's move on and have a look together.

So you should have written the following, for one more you should have got five add nine is equal 14 for place Value, you should have had 40 add 90 is equal to 130.

For the place value, will be only changed a tens, we'll have 14 add nine is equal to 23, for addition and subtraction inverse you should have 13 subtract four is equal to nine or 13 subtract nine is equal to four.

And one less will be three add nine is equal to 12.

Well done, now that was just a little bit of practise before we move on to independent task.

So what you will be doing today, you're going to be deriving number of facts.

You have the following four equations, 17 subtract nine is equal to eight, six add seven is equal to 13, 14 subtract five is equal to nine and eight add four is equal to 12 and you need to derive the number of the facts using the same headings as before.

Good luck, moment to pause the video and write down your answers.

Well done, and the next following slides, you have the answers to these questions so make sure you pause and take your fix.

Well done, you're nearly at the end of the lesson, if you'd like to share your work, please ask your parent or carer to share your work on Instagram, Facebook, or Twitter, tagging @OakNational and #LearnWithOak.

But before you go, don't forget, it's time to fit in your quiz, well done.

I'll see you again soon, take care.