Lesson video

Hi there.

My name is Mr. Tazzyman, and I'm gonna be teaching you a lesson today from the unit about statistics.

It's a really important unit, and one that will help you to understand things around you through number.

Sit comfortably 'cause we're ready to start.

Here's the outcome for the lesson then.

By the end, we want you to be able to say, I can interpret line graphs representing two variables.

The key words in this lesson are line graph, variable, x-axis and y-axis.

I'd like you to repeat them back to me.

I'll say, "My turn", say the word and then I'll say, "Your turn" and it will be your turn.

Ready? My turn, line graph.

Your turn.

My turn, variable.

Your turn.

My turn, x-axis.

Your turn.

My turn, y-axis.

Your turn.

Here's what those words mean then.

A line graph is a graph where the points are connected by lines.

It shows how something changes in value, usually over time.

A variable is something that changes and can also be measured.

The x-axis is the horizontal line on a graph which goes through zero.

The y-axis is the vertical line on a graph which goes through zero.

You might see a lot of these keywords in maths, but there are lots of other places where they crop up as well.

Those of you who are real scientists, you've probably seen lots of line graphs when you are looking at different sets of data.

Here's the outline then for the lesson.

First, we're gonna start with what is a line graph.

Then we're gonna move on to using a line graph to answer questions.

Sofia, Izzy and Jacob are gonna be joining us today.

They'll be discussing the maths, and they'll give us some hints and tips for our learning, so make sure that you listen carefully because they're ready to start.

I'm ready to start, and you're ready to start.

Let's go for it.

Izzy and Sofia are going to Jacob's house after school.

"We're going to see Jacob's new hamster, Houdini." That's a good name for a hamster.

"I called him that because he keeps escaping from his cage!" "Now that we're in Year 6, we're allowed to walk there on our own." They plot their journey on a line graph, and you can see there we've got two labels on the line graph, time and distance travelled.

The horizontal x-axis is a line measuring time.

Time is a variable.

It's something that changes and can be measured.

The vertical y-axis is a line measuring distance.

Distance is a variable.

The line graph will show how long it took each of us to get to Jacob's house.

"We all travel on the same route, so we each go the same distance." "But we don't travel together." "Some of us take longer to get there than others!" Does that ever happen to you? When you've been on a school trip, are there are a few people who are the stragglers at the end of the line? Hmm.

Jacob sets off straight away.

"He jogs all the way to his house, so gets there first." "I travel the whole distance in a short time." "Then he has to wait at his house for us to get there." "Time passes, but Jacob stays still." "I needed a bit of time to tidy my room." "Jacob is moving around, but he's not travelling any distance." Sofia also sets off straight away.

"She starts walking to Jacob's house." "She travels more slowly than I did," says Jacob.

"I stopped to stroke a cat on the way." "Time passes, but Sofia stays still." "Then she carries on walking, but a bit faster than before." "I was excited about meeting Houdini!" "Sofia arrives at Jacob's house before I did," says Izzy.

Izzy doesn't set off straight away.

"I stayed at school to talk to our teachers about hamsters!" "Izzy sets off later than me or Sofia." "She walks very quickly and nearly catches me up!" "But I had to stop and do up my shoelace." "Time passes, but Izzy stays still." "Izzy is last to arrive at Jacob's house." "Houdini was really cute, but he was also quite sleepy." It's time to check your understanding then.

You can see here that Izzy has drawn a line graph.

"This line graph shows the journey of two characters." "It's from a famous story, which you probably know.

Can you work out which?" "Which character's journey is represented by each line?" "One character, shown by the red line, moves at a constant speed." "The other character, shown by the purple line, stops for a very long time." I wonder why somebody might end up stopping for a very long time.

Okay, pause the video and have a go at working out which line is represented by which character in a famous story.

Good luck.

Welcome back.

Well, this line graph represents the story of "The Tare and the Tortoise".

Did you manage to get that? Hare's journey is shown in purple.

Hare starts quickly, falls asleep, then sprints to the finish.

Tortoise sets off slowly and steadily and does not stop moving.

This is the point at which Tortoise overtakes Hare.

You can see it there.

It's been selected using a black circle.

Tortoise completes the race first and wins.

Okay, it's time for your first practise task then.

The line graph shows four children's journeys from school to the park with their families.

Use the clues to work out whose journey is represented by each line.

A, Andeep starts by walking quickly, but slows down as he travels.

B, Aisha stops once on the journey because her little cousin finds an interesting stone.

C, Jun starts by walking slowly but speeds up as he travels.

D, Laura stops once on the way, but arrives at the park before Aisha.

We get a tip here from Jacob.

"Read each clue carefully and look again at the line graph." Okay, it's time for you to have a go then.

Good luck.

I'll be back in a little while with some feedback.

Pause the video here.

Welcome back.

Here are the answers.

Andeep starts by walking quickly, but slows down as he travels.

Andeep must be line one because the line shows less distance being travelled as time passes.

Aisha stops once on the journey because her little cousin finds an interesting stone.

I can't work out Aisha's journey because both two and three show a journey where the traveller stops.

You can see that because the lines momentarily are horizontal.

Jun must be line four because the line shows more distance being travelled as time passes, and Jun starts by walking slowly, but speeds up as he travels.

D, the crucial clue, Laura stops once on the way but arrives at the park before Aisha.

Laura and Aisha both stop on the way, but Laura arrives first, so she must be two and Aisha three.

Okay, pause the video here if you need to discuss any more of those answers.

Alright, let's move on to the second part of the lesson then.

Well done for getting this far.

We are moving on to using a line graph to answer questions.

Line graphs often give more detailed information.

This line graph includes divisions on the x-axis and y-axis.

The variable for the y-axis is mass in grammes and there are divisions every 100 grammes.

Time is still the variable on the x-axis, but it's now measured in months from January to December.

Any point on the line graph has meaning.

Izzy shows Jacob and Sofia this line graph.

"Can you guess what this line graph is showing?? "The graph shows the mass of something changing over a year." "I think it's something alive, but it's far too heavy to be Houdini!" "It actually shows the mass of a hedgehog over a year." Line graph showing the mass of a hedgehog.

There's the title.

"The hedgehog's mass was measured on the first day of each month." "Why is the hedgehog's mass decreasing here?" "Oh, I know! It's because the hedgehog was hibernating." "They 'sleep' through the winter and use up their fat stores." Izzy asks more questions about the graph.

"Can you work out why the hedgehog's mass decreased here?" "Weird! The hedgehog's mass suddenly changed from 700 grammes to 600 grammes." "I'll give you a clue.

The hedgehog is a female." "I know! It's because the hedgehog had babies." "Well done! What was the mass of the hedgehog at the start of April?" "This is April.

This is the mass at the start of April." "At the start of April, the hedgehog's mass was 500 grammes." "Estimate the mass at the hedgehog at the beginning of June." "This is June." "This is the mass at the start of June." "The hedgehog's mass is between 700 grammes and 600 grammes.

It's slightly nearer 600 grammes.

At the start of June, the hedgehog's mass was approximately 640 grammes." Okay, let's check your understanding of what the characters have been talking about so far.

I'd like you to estimate the hedgehog's mass at the start of November.

Pause the video here and give that a go.

Welcome back.

This is November.

You can see it's been circled there.

This is the hedgehog's mass at the start of November, so they've moved up from November until it meets the line.

A good estimate for the hedgehog's mass would be 675 grammes.

You might wanna pause the video here and just compare your estimates with other people around you.

Line graphs are often drawn with straight lines.

"Sometimes you might see them with curved lines." "Line graphs are often more accurate if the lines are curved." But it's easier to draw 'em straight and often easier to read the graphs too." Izzy, Jacob and Sofia look at another graph.

"This graph shows the distance a hedgehog travels in one night." "Hedgehogs are nocturnal, which means they're active at night." "They can easily travel over a kilometre in one night!" That's impressive for little legs.

"How far had the hedgehog travelled by 2:00 AM?" "By 2:00 AM, the hedgehog had travelled 500 metres." "How far had the hedgehog travelled by 11:00 PM?" "I'd estimate the hedgehog had travelled 250 metres by 11:00 PM." Izzy asks more questions about the graph.

"At what time had the hedgehog travelled 700 metres?" This time there's a slight change.

Instead of looking at the time, we are looking at the metres travelled.

"This is 700 metres.

It's halfway between 3:00 AM and 4:00 AM." "That means the time must have been half past three or 3:30 AM." "Estimate how far the hedgehog had travelled by 2:30 AM." "The time here is 2:30 AM." You can see there's been a dotted line drawn halfway between 2:00 AM and 3:00 AM.

"I'd estimate the hedgehog had travelled 550 metres at 2:30 AM." A steep line shows the hedgehog travelling faster.

"Between which times did the hedgehog travel furthest?" "The hedgehog travelled 200 metres between 9:00 PM and 10:00 PM." "The hedgehog also travelled 200 metres between 3:00 AM and 4:00 AM." "You're right! Those were the times the hedgehog travelled furthest." So by looking at where the line was steepest, they were able to see where the hedgehog travelled furthest.

"How far did the hedgehog travel between 11:00 PM and 1:00 AM?" "Well, at 11:00 PM, it had travelled 250 metres and at 1:00 AM, it had travelled 450 metres." "450 metres subtract 250 metres is equal to 200 metres.

The hedgehog travelled 200 metres between 11:00 PM and 1:00 AM.

It travelled 200 metres between these times, but it took two hours to do this." Okay, time to check your understanding then.

Estimate the time the hedgehog had travelled 400 metres.

Pause the video now and have a go.

Welcome back.

"This is the point at which the hedgehog has travelled 400 metres." "Let's draw a line down to the horizontal x-axis, which shows the time." "A good estimate for the time would be 12:30 AM." Okay.

It's time for your second practise task.

The line graph shows turns of Houdini's hamster wheel, so we've got the line graph there with x-axis being labelled as time in hours.

That's our variable on the x-axis and turns of the wheel is our variable on the y-axis.

"Hamsters are nocturnal just like hedgehogs." "Houdini loves being on his hamster wheel." "The hamster wheel helps to keep Houdini fit and healthy!" So that's the line graph that we're gonna be using in this practise task.

You are gonna use that to answer these questions.

A, by what time had the hamster wheel turned 100 times? B, how many times had the hamster wheel turned by 2:00 AM? C, estimate how many turns the wheel had made by 5:00 AM.

D, by what time had the wheel made 350 turns? E, how many times did the wheel turn between 1:00 AM and 6:00 AM? F, estimate how many turns the wheel had made by 12:00 AM.

G, when did the wheel make 100 turns in the shortest time? Don't forget about the steepness of the graph.

Sofia gives us a little tip here and says, "Look carefully at the time and the number of turns of the wheel." Okay, pause the video here and have a go at those.

I'll be back in a little while to give you some feedback.

Welcome back.

Here are the answers for A, 9:00 PM, for B, 400 turns.

"At 9:00 PM, the hamster wheel had turned 100 times.

At 2:00 AM the hamster wheel had turned 400 times." For C, the answer was 425 turns and for D, it was 1:30 AM.

"At 5:00 AM, the hamster wheel had turned about 425 times.

At 1:30 AM, the hamster wheel had turned 350 times." For E, the answer was 150 turns and for F, it was 265 turns.

"At 1:00 AM, the wheel had turned 300 times and by 6:00 AM, it had turned 450 times.

450 subtract 300 is equal to 150.

Between 1:00 AM and 6:00 AM, the wheel turned 150 times.

At 12:00 AM, the hamster wheel had turned between 250 and 300 times.

The answer is closer to 250 than 300, so 265 times would be a good estimate." I suggest, though, that you check with people around you their estimates just to see what reasonable estimate might be.

Pause the video here to do that.

Here's G then.

The answer was between 10:00 AM and 10:30 AM.

"Between 10:00 AM and 10:30 AM, the wheel turns 100 times." You can see that's the steepest part of the graph.

"This is the shortest time in which 100 turns are made." Okay, let's summarise today's lesson then.

A line graph is a way of representing the relationship between two variables.

One variable is represented by the x-axis and the other by the y-axis.

Points are plotted like coordinates with a value on the x-axis and a value on the y-axis.

My name's Mr. Tazzyman.

I enjoyed that lesson.

Hope you did too.

Maybe I'll see you again soon.

Bye for now.