Lesson video

Hello, I'm Miss Mia, and I'm so excited to be a part of your learning journey today.

I hope you enjoy this lesson as much as I do.

In this lesson, you'll be able to use your knowledge of multiplication to solve problems in a range of contexts.

Your keywords are on the screen now, and I'd like you to repeat them after me.

Product, factor.

Fantastic, let's move on.

Now, this lesson is all about using our knowledge of multiplication to solve problems in a range of context, specifically using our knowledge of the twos, fives, and 10 times tables.

So there are two lesson cycles in this lesson.

The first lesson cycle is all to do with word problems. We will be looking at centimetres as our unit, and then for the second lesson cycle, we're still looking at word problems, but this time we're moving from centimetres to metres.

All right, let's get started.

So in this lesson, you'll meet Alex and Jacob.

They're going to be helping us with our mathematical thinking.

Okay, so one sunny day, Pedro was feeling curious about bamboo.

He notices that some species of bamboo grow quite quickly.

Pedro sets off to find which bamboo species grow the quickest so that he can grow more of those.

I think that's very clever.

On his journey across the forest, Pedro stumbles across some bamboo.

Now we've got some bamboo here.

It's two centimetres in length.

Now Jacob says this Bamboo grows two centimetres in the morning, another two centimetres in the afternoon, and further two centimetres in the evening.

What would the total length be? Now the bamboo chute grows two centimetres each time.

It grows two centimetres during the morning, afternoon and evening.

That is three groups of two centimetres.

You can represent this problem in two ways.

You could represent it as a repeated addition, so two plus two plus two, which is equal to or a multiplication equation.

So three times two is equal to.

So two is a factor.

That's because that's the length the bamboo grows over time, and three is a factor.

The three represents the morning, afternoon and evening.

So the stages throughout the day.

So you can skip count in twos to find the total, two, four, six.

The total length would be six centimetres.

So our product is six.

Now Jacob notices something else about the bamboo.

It grows two centimetres during the morning, afternoon, evening and overnight.

That is four groups of two centimetres.

You can write this as two plus two plus two plus two or two four times, two is a factor because that is the length of bamboo grows, and four is a factor, four represents the stages throughout the day.

So morning, afternoon, evening, overnight.

You can skip count in twos to find the total, two, four, six, eight.

The total length would be eight centimetres.

Eight is our product, over to you.

Select the correct multiplication expression for the image below.

Is it A five plus five plus five, B five, five times, or C, four times five? You can pause the video here and click play when you're ready to rejoin us.

So what did you get? C is the correct answer, four times five.

That is four groups of five.

So the five represents the length that the bamboo is growing each time, and the four represents the stages throughout the day.

So morning, afternoon, evening and overnight.

Let's move on, so throughout his exploration, Pedro collects different lengths of bamboo sticks.

So you've got two centimetres there, five centimetres there, and 10 centimetres of bamboo.

Now Pedro begins to organise his two centimetre bamboo sticks in a rather peculiar way.

What is the total length of the bamboo? Well, there are five bamboo sticks.

Each bamboo stick is two centimetres long.

Now I would've got the ruler out and I would've measured it, but I think there's a quicker way we can use our knowledge of multiplication to help us.

So we can write this as five times two.

You can skip count in twos to find the product or the total length.

So let's begin.

Two, four, six, eight, 10.

The total length is 10 centimetres, five times two centimetres is equal to 10 centimetres.

10 is our product.

Now Pedro decides to use all five centimetre bamboo sticks this time, let's see how he organises them.

Oh, very nice.

So what is the total length of bamboo? There are five bamboo sticks.

Each bamboo stick is five centimetres long.

So Jacob says he can write five times five as his equation.

So you can skip count in fives to find the total length or product.

Now, why can Jacob skip count in fives? It's because all the bamboo sticks are five centimetres long and because it's equal groups of five, we can skip count in fives.

Say if one of the bamboo sticks was four centimetres, we wouldn't be able to do that.

So let's begin.

Five, 10, 15, 20, 25.

The total length is 25 centimetres.

Five times five centimetres is equal to 25 centimetres.

Over to you, what I'd like you to do is gather some pencils.

You're going to organise your pencils into a line.

Now, if each pencil was 10 centimetres long, what would the total length of the line be? So it's up to you how many pencils you choose.

But pretend that the pencil is 10 centimetres long and I'd like you to find the total length.

You can pause the video here, off you go.

Now I had a go at this, but I'm just going to show you what I got on the screen.

So for example, I organised my pencils like this.

They were various lengths, but I pretended that each pencil was 10 centimetres long.

I used four pencils.

So there are four pencils each with a length of 10 centimetres.

Four times 10 centimetres is equal to 40 centimetres.

If you had six pencils, you would've skipped counted in 10 because if each pencil is 10 centimetres long, you can do that.

So in skip counting in 10s, you would've got 10, 20, 30, 40, 50, 60.

The total length would've been 60 centimetres.

Let's move on, onto your main task for this lesson cycle.

So question one, you are to gather some pencils, crayons and paperclips.

Pencils are roughly 10 centimetres.

Crayons will roughly be five centimetres, and the length of a paperclip is roughly two centimetres.

Partner A will create a design using one of the items only.

So if partner A chooses pencils, don't swap it because otherwise you will not be able to skip count in equal groups, you will not be able to skip count because your groups will be unequal.

So once partner A has created their design using pencils, for example, partner B will calculate the total length of the design using their knowledge of multiplication.

Partner A will then check the answer.

So for example, Jacob says he will start with pencils first, and that's his design.

That is four pencils.

Each pencil has a length of 10 centimetres.

I can say that the equation is four times 10, the product is 40, so the total length is 40 centimetres.

And Jacob says he can skip count to check.

10, 20, 30, 40.

Yes, you are correct, Alex.

Now for question two, you're going to be answering the following questions.

Pedro the Panda has created more peculiar designs.

Write the multiplication equation for each and find the product.

For one design, he used five bamboo sticks.

Each thick was five centimetres in length.

What is the total length of the design? For his second design, he used five bamboo sticks, each stick was 10 centimetres in length.

What is the total length of the design? And lastly, what do you notice about the two designs? Pause the video here.

Off you go, have fun, good luck.

So what did you get for question one? Here are some examples.

So this time we used five pencils.

So there are five pencils each with a length of roughly 10 centimetres.

That is five times 10.

The total length is 50 centimetres because we could have skip counted in 10s.

So let's do that together.

10, 20, 30, 40, 50, 50 is our product.

So the total length is 50 centimetres.

Then we moved on to using 11 paperclips for this example.

So if the paperclips are roughly two centimetres in length, we can skip count in twos to find the answer.

So the equation here is 11 times two.

11 is one factor because there are 11 paperclips, and two is the other factor, because that is the length of each paperclip.

So the total length is 22 centimetres, and you could have skip counted in twos to find the answer.

Let's do that together.

So two, four, six, eight, 10, 12, 14, 16, 18, 20, 22.

So 22 is the total length.

Now for question two, this is what you should have got.

So for the first question, that is five groups of five centimetres.

You can skip count in fives, five times five is equal to 25.

The total length is 25 centimetres.

For B, that is five groups of 10 centimetres because Pedro is used five bamboo sticks, each stick is a length of 10 centimetres.

So you can skip count in tens.

10 times five is equal to 50.

The total length is 50 centimetres.

Question C, so what did you notice about the two designs? Well, the number of groups or bamboo sticks stay the same.

So one factor is five each time.

The lengths of the sticks in each problem was different.

So one factor was different, the product was also different because of this.

Fantastic, let's move on to lesson cycle two.

This time we're going to be tackling word problems that involve the unit of metres.

So Pedro continues to collect different sized bamboo.

He comes across three larger bamboo sticks.

The total length is 15 metres.

What is the length of each bamboo piece? Well, we can try or skip counting in twos, fives, and 10s to find the length of each bamboo stick.

Alex counts in twos first, so two, four, six.

Well counting in twos shows three times two is equal to six, but our product is 15 metres, so it is not lengths of two metres.

So now Alex trials counting in fives, five, 10, 15, counting in fives shows three times five is equal to 15, which is our product.

So the length of each bamboo stick is five metres.

Later, Pedro comes across four bamboo sticks.

The total length is 40.

So here we know that 40 is the product and four is one of our factors.

So we need to calculate what the length of each bamboo stick is.

Jacob suggests to try skip counting in twos, fives and 10s again to find the length of each bamboo stick.

So he starts by counting on in twos.

So two, four, six, eight.

So counting in twos shows four times two is equal to eight, but our product is 40, so that isn't right.

Now he trials skip counting in fives.

Let's see what happens.

So five, 10, 15, 20.

counting in fives shows four times five is equal to 20, which again is nowhere near 40.

So it's not a product of 40 metres.

That means we now need to skip count in 10s to see if that works.

So let's see, 10, 20, 30, 40.

Fantastic, so counting in 10s shows that four times 10 is equal to 40.

So that means the length of each bamboo stick is 10 metres, over to you.

What I'd like to do is look at the question below.

What is the missing number that we need to calculate? Pedro can see 10 bamboo sticks.

The total length of the bamboo is 100 metres.

What is the length of each bamboo stick? So we've got 10 times something is equal to 100.

Are we trying to calculate A, the product B, the factor, or C, the answer? You can pause the video here, have a think.

So what did you get? Well, the answer is B, factor, and that's because we need to find the total length of each bamboo stick, which is a factor.

We already know the other factor, which is 10, and that's because there are 10 bamboo sticks and the product is 100 because the total length of the bamboo sticks is 100 metres.

Let's move on, a bunch of bamboo sticks have a total length of 30 metres.

Each bamboo stick is 10 metres in length.

How many bamboo sticks is this? Something multiplied by 10 is to 30.

We can use skip counting again, we know we are counting in 10s, but we don't know how many groups we need.

So Alex begins by counting in 10s, 10, 20, 30.

Ah, I said 30, which is our product.

How many groups of 10 is this? Counting in tens shows three times 10 is equal to 30 or three groups of 10.

So there are three bamboo sticks.

So three times 10 is equal to 30.

Next, a bunch of bamboo sticks have a total length of 20 metres.

Each bamboo stick is five metres in length.

How many bamboo sticks is this? Let's look at what we know.

There is a total length of 20 metres.

20 metres is our product.

Then we know each bamboo stick is five metres in length.

That's one of our factors.

We have a missing factor.

We don't know the groups or the number of bamboo sticks.

So Jacob says that he can skip count in fives until he gets to 20 and see how many groups this is.

Five, 10, 15, 20.

Counting in fives shows four times five is equal to 20 or four bamboo sticks that are five metres long makes 20 metres.

So four is the missing factor, over to you.

I'd like you to use skip counting to find the missing factor, which is the length of each bamboo stick.

Pedro can see seven bamboo sticks.

The total length of the bamboo is 70 metres.

What is the length of each bamboo stick? Is it A two, B five, or C, 10? You can pause the video here and click play when you're ready to rejoin us.

So what did you get? Well, you should have got C, 10.

And that's because seven groups of 10 is equal to 70 metres.

And by trialling skip counting in twos, fives and 10s, you would've found that seven groups of 10 is equal to 70.

So let's just check that together.

10, 20, 30, 40, 50, 60, 70.

That is seven groups of 10.

Onto the main task for this lesson cycle.

So for question one, Pedro can see 10 bamboo sticks.

The total length of the bamboo sticks is 20 metres.

What is the length of each bamboo stick? Question two, Pedro can see 12 bamboo sticks.

The total length of the bamboo sticks is 60 metres.

What is the length of each bamboo stick? Question three, Pedro can see nine bamboo sticks.

The total length of the bamboo sticks is 90 metres.

What is the length of each bamboo stick? Question four, a bunch of bamboo sticks have a total length of 35 metres.

Each bamboo stick is five metres in length.

How many bamboo sticks is this? Question five, a bunch of bamboo sticks have a total length of 22 metres.

Each bamboo stick is two metres in length.

How many bamboo sticks is this? You can pause the video here and click play when you're ready to rejoin us.

Off you go, good luck.

So how did you do? Let's have a look.

So for question one, we could have trialled skip counting in twos, fives, and 10s.

So let's try skip counting in twos 10 times and see if we get 20 metres.

Let's begin.

Two, four, six, eight, 10, 12, 14, 16, 18, 20.

So there are 10 groups of two.

10 times two is equal to 20.

The length of each bamboo stick is two metres.

We didn't need to trial skip counting in fives or tens because we already found the length of that.

Now, for question two, let's trial skip counting in twos, fives and tens to find the answer for this one as well.

So we need to skip count in twos 12 times and see what we end up with.

So two, four, six, eight, 10, 12, 14, 16, 18, 20, 22, 24.

Now that's not 60, so we need to skip count in fives now and see if that works.

Let's begin, five, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60.

Ah, that's perfect, 60 is our product.

So by skip counting in fives, we have now realised that five groups of 12 is equal to 60.

So the length of each bamboo stick is five metres.

So for question three, you should have got that nine groups of 10 is equal to 90.

The length of each bamboo stick is 10 metres.

Now let's look at question four.

So a bunch of bamboo sticks have a total length of 35 metres.

So 35 is our product.

Each bamboo stick is five metres in length.

So that's one of our factors.

We need to figure out or calculate how many bamboo sticks this is.

So we can skip count in fives to 35 to calculate this.

So let's begin.

Five, 10, 15, 20, 25, 30, 35.

So I've counted five, seven times.

So that's seven groups of five, which is equal to 35.

That means there are seven bamboo sticks.

And for question five you should have got 11 groups of two.

So 11 times two is equal to 22.

So that is 11 bamboo sticks.

Well done, we've made it to the end of this lesson.

Good job, so let's summarise our learning.

You've used your knowledge of multiplication, specifically our twos, fives, and 10s to solve problems in a range of different contexts.

You should now be able to identify the group size and the number of groups in the problem.

You can then use this to skip count in group size to calculate the product.

Now remember, you can only skip count when the groups are equal.

Well done, fantastic.

Thank you for joining me in this lesson.

Bye.