Lesson video

Hello, everyone.

Welcome back to another mass lesson with me, Mrs. Pocho.

As always, I can't wait to learn lots of new things, and most importantly, have lots of fun.

So let's get started.

This lesson is called, Addition and subtraction within 10, and it comes from the unit, solving problems in a range of context.

By the end of this lesson, you should be able to use your knowledge of addition and subtraction within 10 when solving problems. Let's have a look at this lesson's keywords, part, whole, unknown, and known.

Let's practise them.

My turn, part.

Your turn.

My turn, whole.

Your turn.

My turn, unknown.

Your turn.

My turn, known.

Your turn.

Fantastic.

Let's have a look at today's lesson outline.

So in the first part of our lesson, we're going to be looking at aggregation and partitioning.

And in the second part of our learning, we're going to be looking at augmentation and reduction.

So let's get started with the first part of our learning, aggregation and partitioning.

In today's lesson, you're going to meet all of our Oak children, Izzy, Laura, Lucas, Sofia, Aisha, Sam, Andeep, Jacob, Alex, and Jun.

They're going to be helping us with our learning today.

The children are really beginning to see what Mr. Acorn said the other day.

"Maths really is everywhere." The children line up for lunch, practising their skip counting in twos.

I wonder what maths they'll find during lunchtime.

Two, four, six, eight, 10, 12, 14, 16, 18.

Wait, I just noticed that someone's missing.

They should always count to 20 when they line up for lunch.

"Izzy? There she is." "Sorry, I am here." 20.

Fantastic.

Maybe you could recreate this when you line up to go to lunch.

In the dinner hall, the children line up for their dinners or for their sandwiches.

The children who have dinners line up on the right.

The children who have sandwiches line up on the left.

How many children are lining up all together? It's their first math problem and they've not even got their lunch yet.

Let's use a bar model to help us to represent this problem.

There are three children in the dinner line.

There they are.

And there are four children in the sandwich line.

Let's add that part.

There they are.

So how will we find the whole? Hmm, do you know how we could find the whole? What would we have to do? We can recall that a part plus a part is equal to the whole.

So let's write this as an equation.

If we add three and four, we will be able to find the whole.

Double three is six, and we know that one more is seven because we're adding four.

So seven must be our whole.

Seven children must be in the line.

Now we know that information, let's retell our story.

There are three children in the dinner line.

There are four children in the sandwich line.

There are seven children lining up altogether.

Well done for solving our first problem of lunchtime.

The next lot of children now line up.

How many children are lining up altogether now? Could you show this as a bar model, and write the equation just like we've just done together? Once you found a solution, remember to tell the story just like we did.

Pause this video and come on back once you've shown it as a bar model, written the equation, and practise saying your story.

Welcome back.

Let's see how you got on.

We might have done this.

There is one child in the dinner line.

There are three children in the sandwich line.

So how are we going to find the whole? We know that a part plus a part is equal to the whole.

So let's write that as an equation.

One plus three is equal to the whole.

We can see adding one in any order as one more.

One more than three is four, so the whole must be four.

Let's retell our story.

There is one child in the dinner line.

There are three children in the sandwich line.

There are four children lining up altogether.

Well done if you created that bar model, that equation, and that story.

Let's see what other maths they might find.

Once the children have got their lunch, they sit at the tables.

Five children collect their lunch and sit on the rectangular table.

How many children are still lining up? Hmm, let's represent this math to help us to solve it.

We're going to use a bar model.

There are seven children in the line.

We know that this is the whole, that is all the children that are lining up.

We know that five children sit at the rectangular table, so that is one of our parts.

There they are, look.

We know that the unknown part must be how many children are still in the line.

So how will we now calculate this unknown part? We know that the whole, subtract unknown part, will result in the unknown part.

So let's do that.

Let's write that as an equation.

Seven subtract the five children that sit at the rectangular table, will give us that unknown part.

But how are we gonna calculate that? Can you help us, Alex? Alex knows that seven can be partitioned into five and two.

So he knows that seven subtract five must be equal to two.

There will be two children still lining up for their lunch.

Let's retell our story.

There are seven children lining up for lunch.

Five of them collect their lunch and sit at the rectangular table.

There are two children still lining up for their lunch.

Thank you for your help there, Alex.

Right over to you then.

See if you can solve this similar problem.

Ten children are having their lunch.

Only six children can sit on the rectangular table.

So how many children will be sitting on the circular table? Can you create the bar model like we've just done and work out how many of those children will be sitting on the circular table? Pause this video and come on back once you think you've got an answer.

Welcome back.

I hope you did some great calculating there.

Let's see how you've got on.

We know that there are 10 children having their lunch.

Six of them can sit on the rectangular table, but how are we going to find the unknown part? Let's remind ourselves.

The whole, subtract the known part, is equal to the unknown part.

So let's write this as an equation using our bar model.

We know that the whole is 10 and our known part is six.

So 10 subtract six is equal to what? What calculation are we going to use to solve this? Alex is here to help us out again.

We know that 10 can be partitioned into six and four, so 10 subtract six must be equal to four.

Four children will be sitting on the circular table.

Now we've got a solution, let's retell our story.

Ten children are having their lunch, only six children can sit at the rectangular table.

There they are.

Four children will sit at the circular table.

Well done if you correctly worked out that four children would sit at the circular table.

You are absolutely right.

Well done.

Okay then, over to you with task A.

Using our lunchtime scene, or your own, can you create your own addition and subtraction problems showing this as a bar model and recording this as an equation.

You can also tell your own stories to match the problem that you create.

Alex is here with a stem sentence to help you tell your story.

There are mm and mm, how many are there altogether? Pause this video and come on back once you've had a chance to create your own problems. Welcome back.

Well done for completing your first task.

Let's see how Alex got on with Task A.

Alex tells his story first.

There were five ham sandwiches and four cheese sandwiches.

How many sandwiches were there altogether? Now, he's gonna show how to calculate this.

We know that five is a part because there were five ham sandwiches, and four is a part because there were four cheese sandwiches.

So how are you gonna work that out then, Alex? We know that double four is eight, five plus four is one more, so five plus four must be equal to nine, so there must have been nine sandwiches altogether.

Let's retell our story then, Alex.

There were five ham sandwiches.

There were four cheese sandwiches.

There were nine sandwiches altogether.

Well done, Alex.

Right then, let's move on to the second part of our learning, augmentation and reduction.

Let's get started.

During lunch, the children search for the maths in the room.

Andeep spots the dirty dinner plates piling up.

We have a limit of 10 plates.

Can he put the two plates on the pile and still be within 10? Hmm, I wonder.

Let's do some calculating to see if you can.

The first thing we need to do is to tell the story, because that's gonna help us to visualise this problem.

First, there were seven plates on the pile.

Then Andeep placed two more plates on top.

Now, there are plates on the pile.

How many plates will be on the pile and will it be within 10? Let's work it out.

We're going to use this representation to help us.

We know that there were seven plates at the start of our story because they're already on the pile.

We then know that Andeep places two more plates, so our equation will be seven plus two.

Andeep knows that two more than an odd number is the next odd number, so two more than seven must be nine.

There will be nine plates at the end of our story.

Seven plus two is equal to nine.

Let's put this back into our story.

First, there were seven plates on the pile.

Then Andeep placed two more plates on top.

Now there are nine plates on the pile.

Was it safe for Andeep to put his plates on the plate pile? Hmm, we know that 10 is our limit.

Yes.

Nine is one less than 10, so this is still within 10.

That's the safe number.

Okay then, over to you.

Can you help Sam work out if the pile of plates will still be within 10 if she puts five plates on top? First, there were five plates on the pile.

Then Sam placed five more plates on top.

Now there are plates on the pile.

Can you work out if this will be a safe limit? You might want to represent this problem with a "first," "then," "now" representation like we did previously, and you might want to record this as an equation to help you calculate the sum.

Pause this video and come on back once you think you've got an answer.

Will this be a safe plate pile within 10? Or will it go over? Hmm.

Let's see.

Welcome back.

I'm hoping you've got an answer for Sam.

Let's have a look.

We know that there were five plates on the first pile, and Sam is going to add five more plates, so our equation will be five plus five.

Sam knows that five and five is equal to 10, and she also saw this as double five, which is 10, so there will be 10 plates.

Let's put this back into our story to see if this will be safe.

There were five plates on the pile.

Sam placed five more plates on top.

There are now 10 plates on the pile.

Will this pile be within 10? Yes, 10 is the greatest number that we can have in a pile, so that's the right amount.

Well done, Sam, and thank you to you for helping her.

Okay, let's see what Jacob's now found.

Jacob heads over to the drink station to collect his drink.

If I take four drinks for my table, how many drinks will be left at the station? Hmm, what do we need to do first? Let's tell our story to visualise it.

First, there were eight drinks on the tray.

Then Jacob took four drinks.

Now, there are drinks on the tray.

How many mm drinks will be left? So how are we gonna calculate how many drinks will be left? Let's represent it.

First, there were eight drinks on the tray.

Then Jacob takes four of them, so we're going to subtract four.

Our equation is eight subtract four.

Jacob knows that half of eight is four, so if he subtracts four from eight, it must be four.

There will be four drinks left.

Let's put this information back into our story.

First, there were eight drinks on the tray.

Then Jacob took four drinks.

Now, there are four drinks left on the tray.

Well done, Jacob.

Some really great calculating there.

Okay then, over to you.

Let's tell another story for you to solve.

First, there were six drinks on the tray.

Then Alex took two drinks.

How many drinks are on the tray now? Pause this video and see if you can calculate how many drinks will be left on the tray after Alex takes two of them.

You might want to use a "first," "then," "now" representation, and an equation to help you work this out just like we've done previously.

Come on back once you've calculated how many drinks are going to be left.

Welcome back.

I hope you had lots of fun calculating that problem.

Let's have a look how Alex solved it.

Alex represents it using the "first," "then," "now" representation.

First, there were six drinks.

Then Alex took two of them, so his equation is six subtract two.

How is he gonna work out six subtract two? Alex knows that subtracting two from an even number will give the even number before, so the even number before six is four, so there must be four drinks left.

Let's tell the story with our solution.

First, there were six drinks on the tray.

Then Alex took two drinks.

Now, there are four drinks on the tray.

Well done if you got that there were four drinks left, and well done if you retold the story just like Alex.

Okay then, over to you with Task B.

It's your opportunity to write your own "first," "then," "now" stories.

There are three different scenarios for you to create your own problem.

Then represent these using your "first," "then," "now" representation and show these as an equation.

A, is to write a story about some sandwiches that are taken and eaten.

B, is to write your own story about some drinks being given out.

And C, is a story about some of the nine slices of pizza being placed onto plates.

Pause this video and create your three "first," "then," and "now" stories.

Don't forget to use your "first," "then, and "now" representation and write the matching equation, and solve the problem using your most efficient strategy.

Come on back once you're ready to see how the other children completed it.

Welcome back.

I hope you enjoyed creating your own problems there.

It's fun to create our own problems, isn't it? Let's have a look at how the children got on.

Izzy solved the first problem like this.

First, there were four cheese sandwiches.

Then Izzy takes one sandwich.

She represents this as the equation, four subtract one.

She knows that one less than four is three, so there must be three sandwiches left.

Tell us your story now then, Izzy.

First, there were four cheese sandwiches.

Then Izzy takes one sandwich.

Now, there are three cheese sandwiches left.

Well done, Izzy.

A lovely problem there.

Let's have a look at how Izzy solved the second one.

There were seven drinks.

Then Jacob takes six of them.

Seven subtract six, how are you gonna work it out though, Izzy? Seven and six are consecutive numbers, so they have a difference of one, so we know that there would be one drink left.

Let's listen to Izzy's story.

First, there were seven drinks.

Then Jacob takes six of them.

Now, there is one drink left.

Well done, Izzy.

And finally, the pizza.

Let's see.

First, there were nine slices of pizza, so Izzy went with the whole.

Then three of them were put onto plates, so her equation will be, nine subtract three.

How are you gonna calculate this, Izzy? We know that three and six equal to nine, so nine subtract three must be equal to six, so there would be six slices of pizza left.

Let's recap Izzy's story.

First, there were nine slices of pizza.

Then three of them were put onto plates.

Now, there are six slices of pizza.

Well done, Izzy.

I'm super impressed at all of your hard work.

Thank you for joining me with your learning today.

Let's have a look at what we've learned.

We can see maths everywhere.

We know that a part plus a part is equal to a whole.

And a whole subtract known part can help us to work out an unknown part.

Thank you so much again for your hard work.

I hope this lesson has just showed you that there really is maths everywhere around you.

Make sure to keep your eyes open for any math that's happening in the world around you.

Can't wait to see you again soon.

Goodbye.