Lesson video

Hi everybody, welcome back to your unit on length and perimeter.

So today we are going to be making appropriate estimates of length, and we are going to be then comparing them.

So we are going to be using our centimetre estimators and our measuring brains.

So put on your hats, tighten those ties, and tell the computer "Now I'm a mathematician".

Great, let's get started.

Here is today's Lesson Agenda, first off we're going to do a quick do now, and then look at our star words.

Then we're going to be making estimates and then measuring, and then we're going to be comparing our estimates and measuring before doing our actual measuring.

So today you will need a pencil, paper, ruler, centi, centimetre estimators just like my clip here or if you're lucky to have Dienes at home.

If you need any of those things, please pause the video and grab them before we continue on with the lesson.

Great job, let's get started.

So here we have some pictures and we need to work out what's an appropriate unit of measurement.

For example, would I measure the width of a pencil sharpener in metres? Have a think and pause this video.

Well done, let's have a think together.

So the width of a pencil sharpener I would measure in centimetres because millimetres are going to be far too small.

These are our millimetres, our pencil sharpener would be around the two centimetre mark.

However, the length of a ladybird I would measure in millimetres cause they're very small creatures.

The length of a shoe I would measure in centimetres not metres.

With the height of a double-decker bus, we would definitely measure in metres absolutely.

What about a giraffe? Whisper it.

Would you measure it in centimetres, millimetres or metres? I agree, we would measure in metres.

And the length of a football pitch? Great job, metres.

So here are our today's star words.

Show me your star words, well done.

We have millimetre, centimetre, metre, length, height, width, shorter, greater than, less than, and then we have our hungry hungry crocodiles.

Remember our crocodiles like to face the bigger number because that's the bigger amount they want to eat.

So here we have a Dienes, and what's really exciting about Dienes is that Dienes blocks are actually one centimetre block.

How long do you think there will be on a tens Dienes blocks? Whisper the answer, well done.

Now we would usually be measuring using Dienes blocks however, I don't have Dienes at home so I'm using my centimetre estimator.

This might be a paperclip, it might be a pin, it might be something you have at home, and we are going to be using it today to do some measuring.

So this is our sentence stem, I'm going to show you what you are going to do next.

So here you can see I have a teaspoon, and this teaspoon well, it looks like it is less than a metre and, around 10 centimetres.

Um, my estimate is, hm I think around nine centimetres.

It seems like a sensible estimate to me because it's smaller than a metre but I mean it's still smaller than half a metre.

So what I'm going to do, I'm going to get my estimator and do some measuring.

I can see it's one, two, three, four, five, and a half.

So, using my centimetre estimator, to the nearest centimetre the distance is, well I'm going to round five and a half to six centimetres.

Can you see that what I have done, I have used the sentence stem to help my guiding of measuring.

So I've used my centimetre estimator to measure my spoon, and you're going to be doing this with different household items. Remember to ask permission before you start going through all the drawers.

Pause the video and remember to use the sentence stems. Super job everybody, now that you've finished measuring with your centimetre estimeter, estimator, it's time to use your ruler and to see how accurate we were.

So I'm going to make sure that my end of my ruler matches up with the end of this spoon.

I'm going to use a pencil, oh, my teaspoon is actually a 14 point Hmm, 13.

9 centimetres long.

So to the nearest centimetre, my teaspoon is 14 centimetres long.

Now it's time for you to check the measurements that you made previously with your centimetre estimator.

Great job everybody, give yourselves a big pat on the back.

So the second part of this lesson we are going to be comparing lengths.

So I measured my table earlier and my estimate was that it was around 60 centimetres, but the actual length was 52 centimetres.

So which symbol can we use to represent the comparison? Do I do my crocodile facing 60? Or my crocodile facing the 52? Point to the number my crocodile's going to be facing to.

Absolutely, my crocodile's going to be facing 60 centimetres because 60 centimetres is greater than 52.

So what's the difference between the estimate and the actual length? Well I know I can use my number bonds of ten here because if I know that two add eight is equal to 10, then I know that 52 add eight is equal to 60.

So the difference is eight centimetres.

For your independent task, you are going to be doing the same.

You are going to be measuring items around the house using your centimetre estimator, then you are going to be measuring using your ruler and to the nearest centimetre, and then you are going to be doing the difference between the estimate and the actual length.

You are then going to write number sentences representing that.

For example, 52 is less than 60 so my crocodile is going to be facing 60.

Good luck everybody and have fun measuring around the house.

Remember to pause this video.

Well done everyone, what a super fun lesson we've had today.

If you'd like to, please ask your parental carer to share your work on Instagram, Facebook or Twitter, tagging @OakNational and hashtag learn with oak.

I hope you've had as much fun as I've had today, and I'll see you again soon.