﻿Hi, everybody. Welcome to your unit all about length and perimeter. Today we are going to be measuring to the nearest centimetre and the nearest millimetre. But before we begin, we need to put on your hats, tighten your ties, and tell the computer, "Now I'm a mathematician." Let's get started. So, here is today's lesson agenda. First we're going to be looking at the big picture, our star words. We're going to be using centimetre estimators that we then be introducing millimetres and then it will be time to measure. But before we begin, please make sure you have the following resources. You will need a pencil, paper, ruler, and a pair of scissors. With the scissors, be careful. Make sure to ask your parent or caregiver to help you when using scissors. If you need to get any of these resources, please pause the video now to go collect them. If not, let's get started. Here, we have a beautiful lake in the Lake District. But what can you see in this picture that we might need to measure with? Pause this video and have a think. Exactly, we might want to measure the distance to the shop, we might want to measure the distance up Scafell Pike, and we might want to measure the distance round the lake. Measuring is really important. That's why we need to practise so much. So here are our star words. Oh, I couldn't hear you, star words. Length. Height. Width. Nearest. Measure. Accurately. Ruler. Centimetre. To the nearest centimetre. Millimetre. And to the nearest millimetre. And these are key vocabulary for this lesson. Mr. Mole wants to do some measuring, but he doesn't own a ruler. He is going to find a centimetre estimator. What is your centimetre estimator going to be? I'm going to use one of these teeny weeny pipes. Because I think this is close to being a centimetre. Pause this video to go find your centimetre estimator. Great job. Let's get started. We're now going to measure a piece of A4 paper with our centimetre estimator. How long is it? So I'm going to measure mine. Pause the video and measure yours. Well it's very tricky, isn't it? One. So, my piece of paper, you can see I've drawn little teeny weeny marks along the top. They're telling me how long each centimetre is going to be. So I can see one, two, three, four, five, six, seven, eight, nine, 10, 11, 12. I think this A4 piece of paper is 12 centimetres. I have used my centimetre estimator to measure with it. Now, I'm going to measure my centimetre estimator with my ruler. How long is it going to be? I'm going to need your help, with this one. Here is my centimetre estimator, and let's see how long it is. So I'm going to get my ruler and line it up really, really carefully. So the bottom, it starts on the centimetre. Oh no! It's so much bigger than a centimetre. It's two and a half centimetres. Hey you see I have a strip of paper and I'm going to carefully measure, using my centimetre estimator. So, I'm going to mark the ends, that's one. Really carefully move it, two. Three. Four, and a half. So my estimate, is four and a half centimetres. So now, I need to check my ruler, how long it actually is. I'm going to carefully put the end there. Oh my goodness, I can see it's a lot bigger. It's almost 12 centimetres. So it is 11, 11.7 centimetres. I wasn't very accurate was I? Hopefully, your measurements will be a lot more accurate with your centimetre estimators. Good luck and don't forget to pause the video. Great job everybody. Now let's keep going because now we're going to be looking at a measurement called millimetres. So here, we have a close-up version of a ruler. Now, what is the unit of measure represented by the smaller marks between the centimetres? The little dashes between the centimetres are known as millimetres. And in each centimetre there are 10 millimetres. So repeat after me. There are 10 millimetres in one centimetre. Again, 10 millimetres in one centimetre. One centimetre is 10 millimetres. Well done. So, here you can see I've drawn a red line on my ruler. What measurement is it showing in centimetres? Pause this video and carefully look at the ruler. Great job. It is three and a half or 3.5 centimetres. What would that be in millimetres? Well, if I know that 10 millimetres is the same as one centimetre, then I know that 20 millimetres is the same as two centimetres. And 30 millimetres is the same as three centimetres. And because I have that half, I can count those little dashes So we're 30, 31, 32, 33, 34, 35 millimetres. So three and a half centimetres or 3.5 centimetres, is the same as 35 millimetres. Here, we can see what's the same and what's the difference between millimetres and centimetres. We have our millimetres which are represented by mm, centimetres which is represented by cm and metres which is represented by metres. So we know, there are 10 millimetres in one centimetre and there are 100 centimetres in one metre. For your independent task today, you are going to be doing some measuring. You need to cut out five different strips lengths. Please ask a guardian or carer to help you and then you're going to measure them with your ruler to the nearest millimetre and to the nearest centimetre. Remember to carefully use your ruler, line it up at the end just like we talked about, and then keep measuring. Good luck. Remember to pause the video. Great job, everyone. I hope you had fun measuring today. If you'd like to, please ask your parent or carer to share your work on Instagram, Facebook, or Twitter tagging @OakNational and #LearnwithOak. I had fun with you today and I can't wait to learn with you another day soon. See you soon and take care.

1cm is equivalent to 10mm

2 cm is equivalent 2mm

5cm is equivalent to ...

5.5cm is equivalent to...

40mm is equivalent to...

80mm is equivalent to...

Measuring lengths to the nearest cm or mm

In this lesson, we will learn how to use our rulers accurately and begin measuring in cm and mm

Lesson overview:Measuring lengths to the nearest cm or mm

Core Content

Length and perimeter: