Lesson video
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Hi everybody.
Miss Hill here.
Today we are going to be calculating the perimeter of 2D shapes in mixed units.
So let's get started.
Put on your hats.
Tighten those ties.
And tell the computer, now I'm a mathematician.
So here is our lesson agenda for today.
We're going to start off the lesson with the "Do Now" and our "Star Words" before working out perimeters and centimetres and millimetres before you go off to do your independent task.
But before we begin, please make sure you have a pencil, a piece of paper, and a ruler in front of you.
If you need to collect these things please pause the video now.
Super duper.
Here is your Do Now for this lesson.
Calculate the perimeters of these 2D shapes.
Pause the video.
Great job everybody.
Let's go through these together.
For the square the perimeter is 20 cm For the rectangle, sorry for the hexagon the perimeter is 40 mm.
And for our rectangle the perimeter is 26 cm.
Let's have a look at our Star Words.
Length.
Total distance.
Altogether.
Calculate.
Perimeter.
Centimetres.
And millimetres.
Super.
Remember we need to use these throughout our learning to help us remember our e-vocabulary.
Can you show me length again? Show me total distance? Show me altogether.
Show me calculate.
Show me perimeter.
Show me centimetres.
Show me millimetres.
Brilliant.
If you see that I'm not using my Star Words actions please remember to give me a whisper reminder through the screen.
So how would we find the perimeter of this shape? We can see this triangle has one side that's 6 cm 2 mm, another side which is 6 cm and 2 mm, and a third side with the base of our triangle which is 7 cm and 4 mm.
So how can we find out the total length of the sides of this triangle? First we need to add the centimetres and then we'll add the millimetres.
So 6 add 6 and 7 is equal to 19.
And 2 add 2 add 4 is equal to 8.
Therefore the total perimeter is 19 cm add 8 mm is equal to 19 cm and 8 mm.
How about this shape.
So we know that we have two missing sides.
And our missing sides are 4 cm and 1 mm and 9 cm.
And first we need to add our centimetres.
4 add 4 add 9 add 9 is equal to 26.
Then we need to add our millimetres, which is just the two 1s.
So 1 mm add 1 mm which is equal to 2 mm.
The total perimeter of this shape is 26 add 2, sorry 26 cm add 2 mm, which is equal to 26 cm and 2 mm.
How about this shape? Now this is a square that's just been turned on it's side.
And we know that a square has got equal sides, so each side is 5 cm and 2 mm.
And the first thing we need to do is to add those centimetres.
5 add 5 add 5 add 5 is equal to 20, and 2 add 2 add 2 add 2 is equal to 8.
Therefore the total perimeter is 20 cm add 8 mm, which is equal to 20 cm and 8 mm.
So now it's your turn to practise what we've learned this lesson.
Pause the video and find the perimeter of these shapes.
Great job everybody.
Let's have a look together.
So here you can see our orange square, the perimeter is 16 cm and 8 mm.
Our blue triangle is 18 cm and 9 mm.
And our pink rectangle is 26 cm and 6 mm.
Great job everybody.
I hope you're enjoying the lesson so far, let's keep going practising measuring in mixed units.
So this is actually your independent task today.
You have got 3 different shapes.
You have a pentagon, you have a triangle, and you have a hexagon.
Each side of this pentagon has a length of 7 cm and 1 mm.
What is the perimeter of this pentagon? So you need to make sure you calculate the perimeter of each side before adding them up and then finishing off the sentence stem here.
So what you need to do is to pause the video and answer the questions.
Good luck.
Here are our answers.
The perimeter of the pentagon is 35 cm and 5 mm.
The perimeter of the equilateral triangle is 15 cm and 9 mm.
And the perimeter of the hexagon is 12 cm and 6 mm.
Well done everybody, for today's lesson.
If you'd like to please ask you parents or carer to share your work on Instagram, Facebook, or Twitter tagging @OakNational and #LearnwithOak.
Well done for today's lesson, I look forward to learning with you soon.
Bye.
