Lesson video

Today we are going to explore addition and subtraction.

Yesterday we looked at addition equations.

Today we're going to be looking at addition and subtraction equations, and using all of the strategies that we've used and looked at over the last few lessons.

Now, this is lesson eight for the topic of addition and subtraction.

You will need a paper and a pencil.

There are times when you will have to pause the video to have a go at some of the activities yourself.

Now, let's get started.

We are going to be looking at a key vocabulary, that means our star words, identifying if the equation is addition or subtraction, choosing a strategy to solve the problem, working out the answer or missing number, an independent task and checking we've got all of the answers correct.

And finally a quiz to see what we have learnt.

Now let's start with our star words.

Star word, star words.

I'm going to say the star word first.

So it's my turn and then it will be your turn.

Add, subtract, Deans, part, ones, whole, tens, equal.

Super.

Can you show me the add sign? Well done.

Can you show me the subtraction sign? Super.

Can you show me the equal to sign? Good job.

We'll need all of those words for equations today.

Now let's begin today's lesson with a brain warm up everybody.

Let's warm up our brains.

How many ways can I write an equation using addition? I want you to pause the video and have a go.

You will need a pencil and a paper for this activity.

So pause, think, and then write it down.

How did you get on? Did you get all of these different ways? Super work everyone, what a great start to our lesson.

I think we're ready to start.

Oh, following on from our previous lesson, we are going to be doing the inverse.

Oh, I haven't heard that word before.

Inverse is another way of saying the opposite.

So for our learning today, we will be working on the inverse of addition which is subtraction.

So the inverse of addition is subtraction.

So hmm.

How do we convert this addition equation into a subtraction equation? What information do we know that we can use to help us? Hmm, let's see.

So the equation says seven plus six is equal to 13.

Let's see, oh, 13.

I know that 13 is the whole number, which means for our first number, for our subtraction equation, it needs to be 13, because 13 is the biggest number, it is the whole.

So let's write the number 13, and we will be able to take away a part from it.

So if 13 is the whole, what are the parts, can you help me find out? Can you shout them out? Oh, I think you're right.

The parts are seven and six.

Now which one would you like to take away from 13? I'm asking because we could take any of the parts away from the whole.

Can you shout it out, which part you want to take away? Oh, I can hear lots of you shout out seven and six.

I heard six first.

So I'm going to choose the number six.

So 13 subtract six.

Now then, we need to find the answer of 13 subtract six.

To help us, I thought that we could use one of our strategies, and the strategy we could use is we could use a number line.

Here's a number line.

Like in our previous lesson, we need to find the number 13.

Can everyone point to the number 13? Well done.

We've got a number 13, and now we need to make how many jumps? Six jumps.

But can you remember which way we need to do our jumps when we are subtracting? So we need, continue shout out.

We need to go backwards when we're subtracting.

Excellent.

Now, let's make six jumps backwards.

I know we've got Frodo the frog to help us to do some jumps.

Okay, let's see he's ready.

Pointing to the number 13.

Now we need to make six jumps backwards.

Are you ready? Let's count one, two, three, four, five, six.

What number have we landed on? Let's check.

we've landed on the number seven.

Super.

The number seven, just like the number in our addition equation.

That's the last part, so let's write the answer.

Well done.

So now we've got 13 subtract six is equal to seven.

Well done for helping me do the inverse of addition which is subtraction.

Now let's see if you, for another challenge.

At the top of the screen is the equation we've been working on, 13 subtract six is equal to seven.

But what about the equation below? Is it the same as the one above? Let's read it out.

Seven is equal to 13 subtract six.

What is the same or different? And is the equation still correct? I want you to pause the video, think, is it the same or different and then tell the person next to you.

How did you get on? What are your thoughts about the equation? Shall we use the bottom equation and see if it's the same by placing the information on the part whole model? Okay, let's do this together.

What is the whole? Can you shout it out? 13.

Good job.

We know this because when it is a subtraction equation, the whole is the number we are taking away from.

It's the biggest number.

So let's put 13 in the whole.

It's like having 13 sweets and you want to give six to your friend, then you would be left with seven.

So we also know that one part is the amount we are taking away from the whole.

So like the sweets example, the other part is the answer and how many you have left and that needs to come after the equal sign.

So we are taking away six, so like we said take away six sweets, so one part is six, and how many do we have left? We have seven.

Super, so the other part is seven.

So yeah, I agree with you.

It's a different way of ordering the numbers.

But the information stays the same.

Super work everyone.

I wonder if you can help me with the next one.

Oh, dear.

My cat, mr. Cat has mixed up the numbers again.

Can you help me to see what is wrong with the subtraction equation? We have the same numbers in the above number sentence but it doesn't seem right to me.

Can these numbers be moved around like this? I want you to pause, freeze, and have a think.

So pause and freeze macaroni cheese.

How did you get on.

I remarking mind brain and I know something is wrong, but I am not sure what it is.

Can you help me? I hope you can.

Can you tell me what you think is wrong, and I'll try to listen very carefully.

Hmm, I think you might be right.

So you said the whole equation is wrong.

Because six is too small to take away 13 from, which also means that seven couldn't possibly be the answer.

Wow, you really are great mathematicians.

Let's give ourselves a round of applause.

What super work? I agree.

That means we can't just use these numbers and put them anywhere.

We have to make sure the equation works and makes sense.

I think we are ready for an independent task now.

Using all of the information we have just learnt, can you find all the possible subtraction equations to represent these numbers? Thinking about where the whole goes and where the parts go? Task two, can you find all the possible subtraction equations to represent these numbers.

You can use a number line to help you to work out the answers, and you can use the part whole model to find out what is the whole and what are the parts.

Remember, when you do subtraction equation, you have the biggest number, the whole, subtract the part.

Let me know how you get along.

Here are the answers for task one.

Make sure you check yours carefully to look at the whole and the parts.

Here are the answers for task two.

Make sure you check that you've got them in the right orders, and that they make sense.

Wow, you've done super math today and you've done some super hard subtraction equations.

I hope you had lots of fun with learning the inverse of addition, which is subtraction.

Super.

Now I want you to complete your end of lesson quiz to see how much you remembered and I will see you tomorrow.

Bye.