Lesson video

Hello there.

My name is Mr. Tilstone.

I'm a teacher and I feel very lucky and very excited to be working with you today on your maths lesson, which is all about time.

We're going to be looking today at a special kind of clock that you may have noticed, but never really thought too much about.

So if you are ready, I'm ready.

Let's begin.

The outcome of today's lesson is, "I can tell and write the time using Roman numerals." Maybe something you've heard of, maybe not.

And our keywords today, my turn, Roman numerals, your turn.

What are Roman numerals? Well, we're going to investigate now.

It's how ancient Romans used to write numbers.

Our lesson today is split into two cycles.

The first will be recognising one to 12 in Roman numerals.

So without even thinking about clocks.

And the second will be telling the time using Roman numerals.

In this lesson, you're going to meet Laura and Jacob.

Have you met them before? They're very helpful, and they're here today to give us a helping hand with our maths.

You've seen lots of clocks that look like this, but have you ever seen a clock that looks like this? Hmm.

That's different, isn't it? It's very nice.

Very old fashioned looking, isn't it? But have a look at the numbers.

Where are the numbers? The hours are not shown as numbers.

You can see they're in the numbers position, but they're not numbers, or numerals.

The numbers have been replaced by letters.

You might be able to see some letters.

Can you see some letters there? I can see an X, an I.

I can see some more Is, I can see a V there.

So it's got letters on, not numbers.

The number system, you know well, is called the Arabic number system.

It uses the numerals 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

And all of our various numbers are composed from those numerals.

It was first introduced around AD 1200, so about a thousand years ago.

This is not the only way to represent numbers, however, You may have used tallies before.

Have you ever done that? 1, 2, 3, 4, 5.

And the five's a gatepost.

Maybe.

These are Chinese numerals.

Have a look at that.

We're not going to learn about them today, but that's how numerals are represented in Chinese.

And that's just a few of the different numeral systems that exist.

There's lots of them.

But the clock that you've just seen uses what we call Roman numerals, and that's our keyword.

So let's look again.

Roman numerals were replaced by the Arabic number system, but are occasionally still used.

You might see them now and again.

They're not our main number system, but you might still see a few Roman numerals here and there.

And clocks are certainly a place where you can see them.

Sometimes you might see them on the end of films, for example, telling you what year the film was made.

Some people consider them quite a stylish look to have on a clock face.

So that's why people still like them.

They look good.

They look a bit old fashioned, in a nice stylish way.

To make the numbers one to 12 using the Arabic number system, 10 different numerals are used.

0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

And you can make any number one to 12 using a combination of those numbers.

To make the numbers one to 12 using Roman numerals, only three letters are used.

Hmm.

I is one of them.

V is another one.

And X is another one.

So we're going to learn now how we can make the numbers one to 12 just using those three letters.

So let's learn how to form the numbers one to 12 using Roman numerals.

Jacob and Laura are going to see if they can predict the next Roman numeral each time.

And why don't you join in? Why don't you see if you can find some patterns in here? So I is one.

Okay, so that's your first fact.

When you see the letter I, it means one.

Jacob's saying, "That's easy to remember.

They even look a bit similar," don't they? Yes, they do.

There's a resemblance there, isn't there? You can see them.

Same kind of shape.

"So," says Laura, "is 2 V?" 'Cause Laura can remember that V's a Roman numeral.

Is 2 V? No.

It's II.

Hmm.

Jacob says, "So it's like one plus one, I get it." Oh yeah.

So that's how they're making two.

One plus one.

II.

So Laura said, "In that case, three must be III." She's right! "You were right, Laura," says Jacob.

"So 4 then," predicts Jacob, "must be IIII." What do you think? Do you agree? Hmm.

It's not.

That's good logic, isn't it? It was a good prediction, but it's not.

It's IV.

So we're seeing our letter V for the first time here.

There are certain rules in Roman numerals.

Not too many, but their number system is based around rules.

One is that you cannot have the same letter more than three times in a row.

So we can't have IIII, because that's four times in a row.

Three's the maximum.

So see if you can remember that rule.

Four is represented as one less than five.

IV.

One less than five.

That's our first unusual Roman numeral, I would say.

IV.

Four.

But remember the pattern.

So then we've got V, which is five.

So if IV is one less than five, that makes sense that V is five.

"VI then," says Jacob, "must be one more than five, or five plus one." So what do you think? He thinks six is VI.

Agree? Disagree? What do you reckon? Put your thumb up if you agree with him.

Put your thumb down if you disagree with him.

Hmm, let's have a look.

He's right.

Yes it is.

Five plus one.

VI.

Laura says, "I'm getting this now.

VII is seven." Which is like five plus two.

What do you think? Thumb up if you agree, down if you disagree.

VII is seven.

Hmm.

That's right, it is.

Well done, Laura.

"So," says Jacob, "Eight must be VIII, or five plus three." Well, let's have a think.

There's not more than three letters together there, so it's not breaking any rules, is it? And we can see that three is III, and V is five, so why not? What do you think though? Thumbs up or down? He's right, it is.

VIII is eight.

Laura says, "But it can't be VIIII for nine, because that's four of the same letters in a row." So well done, Laura.

She's remembered a rule.

Did you remember that rule as well? Can't be VIIII.

But what could it be? Hmm.

I think there might be a clue in the number four.

IV.

One less than five.

"When the I came before the V," says Jacob, "it meant one less than five.

So IX must mean one before 10, or nine." And he's exactly right! That's it! So IX equals nine, and that means one less than 10.

That's a little harder one to remember.

That's how to write nine.

So now we know nine.

I think you could tell me 10.

"X must be 10," says Laura.

She's right.

Yup, that's it.

Jacob says, "I think 11 will be XI, or 10 plus one." What do you think? Thumb up or down? Hmm.

Is 11 XI? Yes it is.

It's exactly what it is.

Well done, Jacob.

And Laura says, "In that case, 12 must be XII, which is like 10 plus two." Go on then! Thumbs up or down.

What do you think? Let's see.

Yeah, that's right.

Well done, Laura.

So that is our Roman numerals, one to 12.

Have a look at them, learn them, remember the rules.

See if you can remember them even without looking.

And let's do a check.

The Roman numerals have been jumbled up.

Can you work out what each one is, so they're not in any particular order.

So if you've got a partner with you, brilliant.

Work with them.

Go through them.

Can you figure them out? Have you got a good system? Okay, pause the video.

How did you get on? Did you get on well? Let's have a look.

I is one, II is two, III is three, IV is four, V is five, VI is six, VII is seven, VIII is eight.

IX is nine, X is 10, XI is 11, XII is 12.

You might recognise some of these from other things as well, like for example, Henry the Eighth.

I've seen his name spelled Henry VIII.

Eight.

Time for some independent practise.

Let's see if you can put that into action.

A, Jacob says four in Roman numerals is IIII.

Is he right? Explain your answer.

B.

Laura says nine in Roman numerals is IX.

Is she right? Explain your answer.

C, one of these Roman numerals is in the wrong place, bit of an impostor here.

Circle it.

So we've got III, IV, X, V, VI, and VII.

One of them does not belong in that order.

See if you can spot it.

And then D, finally, write the Roman numerals in order from one to 12, just like we just did in the check for understanding.

Okay, I think you've got this.

Pause the video.

Welcome back.

Did you have fun exploring those Roman numerals? Let's have a look.

So for A, Jacob said, four was IIII.

Is he right? No, he's not.

You can't have more than three of the same letters in a row.

You might have said something like that.

It's actually IV.

And B, Laura says nine is IX.

Is she right? Yes, she is.

You can't say VIIII.

Instead you can say IX, meaning one less than 10.

And then say one of these Roman numerals is in the wrong place.

Circle it.

And it's X, because that one, III is three, IV's four, X is 10, V is five, VI is six, and VII is seven.

So that sequence went 3, 4, 10, 5, 6, 7.

And that's obviously wrong, isn't it? You know that.

And then D, the Roman numerals in order from one to 12.

Say them with me.

I is one.

II is two.

III is three.

IV is four.

V is five.

VI is six.

VII is seven.

VIII is eight.

IX is nine.

X is 10.

XI is 11.

XII is 12.

See if you can remember those.

So do you think you're ready now for cycle two? That's where we're going to put that into practise.

We're going to look at those Roman numerals in the context of a clock face.

So see if you can work out what Roman numeral will come next on this clock face.

Now you know those Roman numerals, one to 12.

Here's a clock face.

So one is I, what's two? Shout it out if you know it.

II.

What's three? Shout it.

Well done if you said III.

What's four? Shout it out.

Tricky one this one, isn't it? It's not IIII, it's IV.

Well done if you said that.

What's next? What's five? V.

What's six? VI.

What's seven? Shout it out.

VII.

What's eight, like Henry the Eighth? Go for it.

VIII.

Well done if you said that.

Right, tricky one coming up now.

What's nine? And I'll give you a clue.

One less than 10.

Go! Well done if you said IX.

That was a tricky one.

Right, you should know 10.

Go! X.

Well done.

11's quite easy, I think.

Off you go! XI.

And then finally, what would 12 be? Go for it.

XII.

So have a look at that clock face.

Have you seen a clock face that looks a bit like that before? That doesn't have Arabic numerals on.

That's got Roman numerals on.

Hmm.

They're quite common.

So the numerals are the only change to the clock and how the time is told.

So all the other skills that you already know all still apply.

Everything that you know about telling the time still applies.

It's just that the numbers are in different form.

The numerals are in a different form.

So that's still one o'clock, that's still two o'clock, three o'clock, four o'clock, five o'clock, six o'clock, seven o'clock, eight o'clock, nine o'clock, 10 o'clock, 11 o'clock, 12 o'clock.

Nothing's changed.

Just the way the numbers are represented.

So just like before, the hour number can also be used to tell us how many minutes have gone past the hour, or how many minutes there are to the next hour.

So we've got five minutes past one.

10 minutes past one.

Quarter past one.

So have a look.

So that minute hand is pointing to the three.

III means three, and when it's pointing to three, that means 15 minutes have gone past, and that's the same as quarter past, which I bet you already knew.

Okay, it's pointing to four.

That's 20 minutes past.

20 minutes past one.

Pointing to 5, 25 minutes past one.

Pointing to six, half past one, or 30 minutes past one.

Pointing to seven.

That's like 35 minutes past, or better still, 25 minutes to.

So that's 25 minutes to two, 20 minutes to two, quarter to two, which is like 15 minutes to two, 10 minutes to two, five minutes to two.

And two o'clock.

So nothing, nothing at all has changed.

Just the way the numerals are represented.

That's all.

So you haven't got lots of new skills to learn.

Let's do a check for understanding.

You've got a paper clock, and it's got the Roman numerals on.

Use a paperclip to represent the hour hand, 'cause it's nice and short, and a pencil to represent the minute hand 'cause it's nice and long and thin.

Show me.

Are you ready? Show me 20 minutes to five.

Pause the video.

Where did you put that paperclip and that pencil? Hmm, pencil should be pointing there to the number eight, which is VIII.

Because that's 20 minutes to, 40 minutes past.

And then the five, think about that.

20 minutes to five.

So it's not reached five yet.

It's gonna be in between four and five, and that's four and that's five.

So it should look something a bit like this.

So that's just like I'll ask you to do 20 minutes to five on any other clock.

Just a different representation of the numerals.

Well done if you got that.

You may wish to carry on and practise with some other examples, or you may wish to continue with me with the next part of the lesson.

Jacob and Laura are playing a game.

Jacob's describing what is on his clock face, and he reads the letters of the Roman numerals instead of saying the numbers.

Laura has to say the time.

Okay, so he says, "The minute hand is on the IV." Now you wouldn't normally say it as IV.

You'd normally say what the number is, but that's what he's saying.

It's giving her a clue.

"The minute hand's on the IV, and the hour hand is between VIII and IX." Okay, and she's got the clock to look at there, as she goes through these clues, she can look at the clock, the minute hand's on the IV.

Now look at that.

Hour hand's between VIII and IX.

She says, "Hmm, IV is four.

And when the minute hand is on four, it's 20 minutes past." Hmm.

Yes, I agree.

"VIII is eight, and IX is nine." So it's in between those two.

"Is your clock showing 20 minutes past eight?" "Yes!" says Jacob.

"Well done, Laura." Let's do a check.

Going to do something very similar.

You might want to use your clock that you've got in front of you, your paper clock.

You might even be able to visualise it and picture it.

Who knows? Okay, so it's the same stem sentence.

The minute hand is on "mm", and the hour hand is in between "mm" and "mm".

Let's fill it in.

The minute hand is on IX, and the hour hand is in between IV and V.

What's the time? Pause the video.

Did you get it? Let's have a look.

It's quarter to five, or 45 minutes past four.

We would tend to say quarter to five though.

Well done if you got that.

And that's what that looks like on a clock.

Again, you might want to practise with some other examples.

Feel free to do that.

Or you might want to carry on with me now.

Time for some practise, and more practise.

So number one, read the time on these clocks.

What does it say? Now, remember what I said before.

This is not different than normal clocks.

If you could do this on other clocks, you can do it with Roman numeral ones too.

So what's the time? And then for number two, you're going to draw the time on the clocks using both hands.

Remember, the long hand, the big hand, is minutes, and the short hand is the hour hand.

So have a go at drawing those hands.

And then number three, with your partner, practise making different times using the stem sentences.

Show me "mm" minutes past "mm", or show me "mm" minutes to "mm." So use your paperclip and your pencil and your paper clock face.

So in this example, Izzie's saying, "Show me eight minutes to three." And that's exactly what Andeep's done.

And for number four, describe a time to your partner using the stem sentence.

Read the letters of the Roman numerals aloud.

Keep swapping over.

So the minute hand is on "mm" and the hour hand is in between "mm" and "mm".

And again, you might want to use your clock in front of you, or you might even be able to picture it and visualise it in your head.

Okay, good luck.

Have fun.

See you soon.

Welcome back.

How did you get on? Let's have a look.

So the time on the clock, that's half past three or 30 minutes past three, that's 20 minutes past one.

We'll also accept 20 past one, that's fine.

And this one is nine minutes to 12, but 51 minutes past, although a bit unconventional, is acceptable.

And then the hands look like this.

That is quarter past seven, that is 12 minutes past 10, and that is 30 minutes to three.

So they're the exact positions for your hands to be in.

Well done if you got those.

And then there's lots of possible responses you could have had to this one.

Lots of things you could have asked your partner.

Might have been something like, "Show me 12 minutes past six." That's what Izzie's asking Andeep.

And he's doing 12 minutes past six, so he's got that one right.

And then number four, again, lots of possibilities here.

You might have said something like, "The minute hand's on V, the hour hand is in between VI and VII." And that will make that 25 minutes past six.

We've come to the end of the lesson.

I've had great fun with this lesson.

We've been telling and writing the time, including using Roman numerals.

Some clocks show Roman numerals in the place of hours.

Some people just like their look of it.

It looks nice.

You can still use the same time telling skills even when the clock face is displayed in this way.

So everything you learned before still applies.

They just look a bit different.

I've had great fun working with you today, and I really hope I get the chance to work with you again in the near future.

But until then, enjoy the rest of your day, whatever you have in store, take care, and goodbye.