Lesson video

Hi everybody.

Welcome back to your unit on length and perimeter.

Today, we are going to be calculating the perimeter of shapes in metres and centimetres, so let's get started! Put on your hats, tighten those ties, and tell the computer now I'm a mathematician! Brilliant, let's get started with the lesson.

So here is today's lesson agenda.

First we're going to do a quick do now then we'll do our star words, finding perimeters of shapes, then it'll be your turn, then it'll be the independent task.

But before we get started, please make sure you have the following three things in front of you.

A pencil, a piece of paper and a ruler.

If you need to go get anything, please pause this video and go get it now.

Great, let's get started.

Here is our do now.

Put these sets of lengths in order from shortest to longest.

So pause this video and put these sets of lengths in order from shortest to longest.

Great job.

Let's have a look together.

So our first one we have 1 metre and 80 centimetres, 1 metre and 87 centimetres and 2 metres and 16 centimetres.

Our second one, 1 metre and 19 centimetres, 1 metre and 93 centimetres and 204 centimetres which is the same as 2 metres and 4 centimetres.

And finally, 130 centimetres, 113 centimetres and 0 metres and 67 centimetres in order from shortest to longest is 0 metres and 67 centimetres, 113 centimetres and 130 centimetres.

Great job everybody.

Here we have our star words.

Can't hear you? Star words! Perimeter.

Measure.

Length.

Total distance.

Altogether.

Calculate.

How can I find this perimeter? Well we can see that we have two different measurements here.

We have 6 metres and 10 centimetres and we have 2 metres and 5 centimetres.

So first we need to add the metres and then we're going to add our centimetres.

So our metres are 6, 6, 2 and 2.

So 6 + 6 + 2 + 2 is equal to 14 metres.

And then we need to add the centimetres.

10 centimetres + 10 centimetres + 5 centimetres + 5 centimetres is equal to 30 centimetres.

Have we finished? No, We've got to put the measurements together.

So the answer is 16 metres and 30 centimetres.

How about this one? Now remember, this is a square.

And on a square, lengths of the sides are the same.

So pause the video and have a go.

Great job everybody, let's see if we got the same answer.

So I know, that on the square all the sides are equal.

So they are all 5 metres and 20 centimetres.

So we need to add our metres first.

So 5 + 5 + 5 + 5 is equal to 20.

Then we add our centimetres which is 20 + 20 + 20 + 20 which is equal to 80.

So the answer is 20 metres and 80 centimetres.

Now it's your turn.

You have three shapes here.

You have a rectangle, you have a square and you have a hexagon, a six sided shape.

Now, find the perimeter! Pause the video.

Super.

Let's go through these answers together.

Here we can see our rectangles perimeter is 14 metres and 70 centimetres, our hexagon is 30 metres and 60 centimetres and our square is 48 metres and 20 centimetres.

Give yourselves a big one, two, three well done me! Super job.

Here we have our triangle and we can see that is has a side that is 3 metres and 40 centimetres and we know that we need to add our three sides together and because it's an equilateral triangle they are all 3 metres and 40 centimetres.

So we're going to add the metres first, so 3 + 3 + 3 is equal to 9.

Then we need to add 40 centimetres + 40 centimetres + 40 centimetres which is equal to 120 centimetres which is in fact 1 metre 20.

So if we add 1 metre 20 to 9, we get 10 centimetres, sorry, 10 metres and 20 centimetres.

Here we have a rectangle.

My rectangle has got one side which is 2 metres and another side which is 4 metres and 50 centimetres and two blank sides.

What we know about these sides is that they will be the same lengths as it's opposite.

So this side would be 2 metres and this side would be 4 metres and 50.

So we're going to add our metres together, 4 + 4 + 2 + 2 is equal to 12.

Then we're going to add our centimetres together and 50 centimetres + 50 centimetres is equal to 1 metre.

Add the two together, 13 metres.

For your independent task today, you are going to be finding the perimeters of these three shapes.

So, pause the video and find these shapes' perimeters.

Great job everybody.

Let's go through the answers together.

Here we have our rectangle and our rectangle has got two sides that we can see.

One is 43 metres and 25 centimetres and the second is 57 metres and 20 centimetres.

Now we know we need to do quite a lot of adding here, but we're going to add the metres first.

So 57 + 57 + 43 + 43 is equal to 200.

Then we're going to add the centimetres which equal to 90 centimetres.

Add the two together, 200 metres and 90 centimetres.

Here we have our square, remember we need to add the squares together.

Sorry, add the lengths of the square and they are luckily they're all equal.

So all the sides are 2 metres and 30 centimetres.

First, let's add the metres.

2 + 2 + 2 + 2 is equal to 8.

Then we're going to add the centimetres which is equal to 120 centimetres or 1 metre 20.

So we're going to add them together.

8 metres + 1 metre 20 which is equal to 9 metres and 20 centimetres.

And finally, this is our next shape.

So remember, all the sides are equal.

So we're going to add the metres and the five sides of this pentagon is equal to 150 metres.

And then we're going to add the five sides of 15 centimetres which is equal to 75 centimetres.

Add the two together, we have 150 metres and 75 centimetres.

Great job everybody that was a lot of adding big numbers today.

If you'd like to, please ask your parent to career to share your work on Instagram, Facebook or Twitter tagging @OakNational and #LearnWithOak.

Well done, I look forward to learning again with you soon.

Take care.