Lesson video

Hello, everyone.

Welcome back to another math lesson with me, Mrs. Pochciol.

As always, I can't wait to learn lots of new things and hopefully have lots of fun.

So let's get started.

This lesson is called calculate the difference when information is presented in a bar chart and it comes from the unit calculating within 20.

By the end of this lesson, you should be able to calculate the difference when information is presented in a bar chart.

Let's have a look at this lesson's keywords.

Bar chart, difference, counting on and subtraction.

Let's practise.

My turn, bar chart.

Your turn.

My turn, difference.

Your turn.

My turn, counting on.

Your turn.

My turn, subtraction.

Your turn.

Fantastic.

Now that we've practised them, let's use them.

Let's have a look at our lesson outline.

In the first part of our learning, we're going to be exploring bar charts.

And in the second part of our learning we're going to be interpreting information from our bar chart.

So let's get started with the first part of our learning, exploring bar charts.

Laura and Andeep are back to help us with our learning.

Are you ready, guys? Let's go.

The children complete their weekly litter pick and record the amount they pick up on a bar chart.

How much litter did Laura pick up then? Let's have a look.

Andeep notices that Laura's bar goes up to nine.

So that must mean that Laura picked up nine pieces of litter.

She did.

Well done, Andeep.

So did Andeep pick up more or less litter than Laura? Let's have a look.

Andeep's bar doesn't go up as high as Laura's bar.

So does that mean that he picked up more or less litter? That means that he must have picked up less litter.

He actually picked up six pieces of litter.

Can you see? Because his bar goes up to six.

Andeep knows that Laura picked up more litter, but he wants to know how many more pieces Laura picked up than him.

We can see that Laura picked up nine pieces and Andeep picked up six pieces.

So if we calculate the difference, that will tell us how many more pieces of litter Laura picked up than Andeep.

We can see nine, the amount that Laura picked as our whole and six, the amount that Andeep picked as a part.

The difference between these will be at other part, the unknown part.

We know that to calculate the difference we can subtract the smaller number from the larger number.

We can see six as a part and nine as the whole.

So whole subtract part is equal to the unknown part or in this case our difference.

So nine subtract six.

How we're going to work that out then, guys? We know that nine subtract six is equal to three.

So the difference between six and nine must be three.

That means that Laura picked up three more pieces of litter than Andeep.

Wow, I love how you applied your difference knowledge to that bar chart, guys.

Well done.

Over to you then.

How many more pieces of litter did Izzy pick up than Jun? Can you show the equation that you use to solve this? You might want to represent this as a bar model as it might help you to visualise this problem.

Pause this video.

Have a go at finding out how many more pieces of litter Izzy picked up than Jun and come on back to see how you got on.

Welcome back.

Let's have a look then.

Andeep created a bar model to help him to visualise this problem.

Jun had a part which was five.

Izzy had the larger number so we can see her 10 as the whole.

We know that the difference between five and 10 will be the other part.

10 subtract five is equal to five, as we know that half of five is 10.

So we can see that the difference between 10 and five must be five.

So what does that mean then, Andeep? That means that Izzy picked up five more pieces of litter than Jun.

Well done to you if you got that.

Andeep now has another look at the bar chart.

He can see that Izzy picked up the most litter.

He wonders how many fewer pieces of litter he and Laura picked up compared to Izzy.

Laura suggests that they work it out.

They create bar models and write the equation to show their calculations.

To see how many fewer, we need to subtract our numbers from 10.

We can see that Izzy picked up 10 pieces, so we are going to see her number as the whole.

Laura picked up nine pieces of litter and Andeep picked up six pieces of litter.

To find their difference, they're going to subtract the parts from the wholes.

So the whole, which is 10, subtract Laura's part, which is nine is equal to one because we know that nine is one less than 10.

Well done, Laura, I love how you used your one less knowledge there.

Andeep is now going to subtract his part from the whole.

10 subtract six is equal to four.

He didn't need to do any calculating there because that's another number pair to 10.

We know that six and four are a number pair to 10, so 10 subtract six must be equal to four.

Laura can now see that she picked up one fewer piece than Izzy and Andeep can now see that he picked up four fewer pieces than Izzy.

Oh Laura, you are so close to beating Izzy.

One piece more piece and you would've had the same.

Over to you then.

How many fewer pieces of litter did Jun pick than Sam? Can you represent this as a bar model and show the equation that you used to find the solution? Pause this video and find out how many fewer pieces then come on back to see how you've got on.

Welcome back.

Let's have a look then.

Let's show this as a bar model, Andeep.

We know that Jun collected five pieces of litter, so that's his bar.

We know that Sam collected seven pieces of litter.

Seven is more than five, so we can see seven as our whole.

The unknown part will be the difference between five and seven.

If we subtract five from seven, that will give us the difference.

Seven subtract five, come on then, Andeep.

We know that five and two more is equal to seven.

So seven subtract five must be equal to two.

Sam picked up two more pieces of litter than Jun.

Well done to you if you've got that correct.

Aisha now comes along and adds her number to the bar chart.

Laura now wants to calculate the difference between Aisha's number and her and Andeep's number.

Andeep notices that Aisha picked up more litter than him but less litter than Laura.

We can see that Laura picked up nine pieces of litter and Aisha picked up eight piece of litter, so we can see that that is one more.

The difference between their numbers is one.

We can see that Andeep picked up six pieces of litter and Aisha picked up eight.

We know that they are consecutive even numbers, so that means that their difference must be two.

Wow, guys, you didn't even have to do any calculating there.

Well done.

I'm really impressed.

Laura explains that they didn't need to use any calculating here because they know their number facts within 10.

Remember how important it is to remember those facts because it just saves us a lot of time rather than having to calculate.

We can just know the fact.

Andeep does make a good point though, the strategies that we've been practising to calculate difference will definitely help us when we're working with larger numbers.

Over to you then.

Sam calculates the difference between her number and Aisha's number.

She says that the difference between seven and eight is one and records this calculation as an equation.

Seven subtract eight is equal to one.

Is she correct? Pause this video.

Have an explore of Sam's working and come on back when you think you can tell her whether she's correct or not.

Welcome back.

Let's have a look then.

Did you think Sam was correct or not? Andeep, what did you think? Andeep knows that the difference between seven and eight is one, but subtraction isn't commutative so we must start with the larger number.

So although your statement is correct, Sam, the difference between seven and eight is one.

Your equation wasn't quite correct.

It should have been eight subtract seven equals six because subtraction isn't commutative.

Can you have a go at fixing it, Sam? There we go.

Eight subtract seven is equal to one.

Well done to you if you spotted that Sam's equation wasn't correct.

Over to you then with task A.

Task A is to find the solutions to these questions and write an equation to show you are working for each one.

A, how many more pieces did Andeep pick up than Izzy? B, how many fewer pieces did Jun pick up than Sam? C, what is the difference between Laura's number and Aisha's number? And D, what is the difference between the greatest and the smallest number of litter picked? Hmm.

Pause this video.

Have a go at task A and come on back when you're ready to find out how you got on.

Welcome back.

Let's have a look then at task A.

A then, how many more pieces did Andeep pick up than Izzy? We can see that Andeep picked up eight pieces and Izzy picked up three pieces.

If we calculate the difference, we will know how many more.

Eight subtract three is equal to five.

So we can see the difference between eight and three is five.

That means that Andeep picked up five more pieces of litter than Izzy.

Well done if you got that one.

B, how many fewer pieces did Jun pick up than Sam? Jun picked up six pieces of litter and Sam picked up 10 pieces of litter.

Remember, the larger number is written first in the subtraction.

So although we're thinking about six compared with 10, we'll record this subtraction as 10 subtract six, which we know is four 'cause that's a number pair to 10.

The difference between six and 10 is four.

So that means that Jun picked up four fewer pieces of litter than Sam.

Well done if you got that one.

And C, what is the difference between Laura's number and Aisha's number? We can see that Laura picked up five pieces of litter and Aisha picked up nine pieces of litter.

Remember, difference is the answer to a subtraction.

So nine subtract five will be equal to four.

That tells us that the difference between nine and five is four.

So the difference between Laura and Aisha's number is four.

Well done if you got that one.

And D, what's the difference between the greatest and the smallest number? We can see that the greatest number is represented by the tallest bar and the smallest number, the shortest bar.

So Sam has the greatest number, which was 10 because that's the tallest bar.

Let's have a look then.

The shortest bar is Izzy, which is representing three because we can see that that's the shortest bar.

Laura noticed that this was another pair to 10.

We know that seven and three are equal to 10, so we know that the difference between 10 and three is seven.

So the difference between the greatest and the smallest number must be seven.

Well done if you got that one correct and well done for completing task A.

Let's move on then to the second part of our learning.

Interpreting information from a bar chart.

Let's go.

Mr. Acorn creates a bar chart to represent the next week's litter pick.

There's something different about this bar chart.

Andeep notices that the scale now goes up to 20.

Does that mean that we have to look at this bar chart any differently? No.

It doesn't change anything about the bar chart.

We will still read it the same.

Let's practise.

How many pieces of litter did Andeep pick up? Well, let's have a look at the bar chart.

The bar chart goes up to here and I can see that that reaches 12.

So that means that you picked up 12 pieces of litter, Andeep.

Well done.

I love how you read that bar chart there, Laura.

Shall we have a practise and an explore of this bar chart? Over to you then.

What other information can you gain from this bar chart? Use these stem sentences to help you.

Mm picked up mm pieces of litter in this week's litter pick.

Mm picked up the greatest number mm pieces of litter.

And mm picked up the smallest number mm pieces of litter.

There's some things that you might like to explore with this bar chart.

Pause this video and come on back once you've had chance to create some of those stem sentences.

See you soon.

Welcome back.

I hope you enjoyed exploring that bar chart.

Let's see how Andeep got on with finding the information from this bar chart.

Sam picked up 13 pieces of litter in this week's litter pick.

We can see, look that Sam's Bar goes up to 13, so yes, that's correct, Andeep, well done.

Oh, Izzy picked up the greatest number, 20 pieces of litter.

Look, Izzy's goes all the way to the top of our bar chart.

So yes, 20 pieces is what she picked up.

Well done, Andeep.

And Jun picked up the smallest number, nine.

Let's have a look.

Yes, that is the shortest bar and we can see that that goes up to number nine on our scale.

So yes, Andeep, you're correct.

Well done to you if you said any of those stem sentences.

Andeep notices again that Laura has picked up more litter than him, but he wants to know how many more pieces did she pick up than him.

Laura says that she picked up 18 pieces and Andeep picked up 12 pieces.

So we're going to calculate the difference to find out how many more pieces.

We can see 18 as the whole and 12 as the part.

The whole subtract the part will be equal to that unknown part or in this case the difference.

To calculate the difference, we can subtract the smaller number from the larger number, which is 18 subtract 12.

Andeep's going to use a count on strategy here because they're quite close together.

12 and six more is equal to 18.

Andeep counted on six more, so we know that the difference between 18 and 12 is six.

So that means that Laura picked up six more pieces of litter than Andeep this time.

Well done, Laura.

Come on Andeep.

I think you can beat her next week.

Over to you then.

What is the difference between Jun and Andeep's number? Pause this video.

Have a look at Jun and Andeep's numbers and come on back when you can tell me what the difference is between their two numbers.

Welcome back.

Let's have a look then.

What is the difference between Jun and Andeep's numbers? Jun picked up nine pieces of litter and Andeep picked up 12 pieces of litter.

We can see nine is our part and 12 is our whole.

The whole subtract the part will give us the other part, which in this case is our difference.

12 subtract nine.

How you're going to work that out, Andeep? We can count on from nine through to 12.

We can see that the difference is three.

So 12 subtract nine must be equal to three.

The difference between Jun and Andeep's numbers is three.

Well done to you if you've got that.

Andeep now notices something.

We can see the scale as a number line that runs up and down.

Andeep can see the difference between his and Jun's number.

Look, it's 3, 9, 10, 11, 12.

It's like a number line.

Andeep practises what he has noticed, counting on from 13 through to 20, we can see the difference between Sam and Izzy's numbers.

There are seven steps on our number line.

So 13 plus seven is equal to 20.

The difference between 13 and 20 is seven.

So we can say that Izzy picked up seven more pieces of litter than Sam, or we can say that Sam picked up seven fewer pieces of litter than Izzy.

Wow.

I love how you're using the bar chart there.

That saves us a lot of time with calculating.

If we can see the difference on the scale.

Well done, Andeep.

A really useful thing to notice there.

Over to you then with task B.

Find the solutions to these questions and write an equation for each.

A, how many more pieces of litter did Aisha pick up than Andeep? B, how many fewer pieces of litter did Sam pick up than Jun? C, what is the difference between Laura's number and Izzy's number? And D, what is the difference between Laura's number and Sam's number? Remember to use all of those wonderful strategies that we've looked at throughout our learning today.

Come on back once you've had a go at all of those questions.

Welcome back.

Let's have a look then.

A, how many more pieces of litter did Aisha pick up than Andeep? Hmm, we can see Aisha picked up 20 and Andeep picked up 10.

20 subtract 10 is equal to 10 because we know that 10 is half of 20, so the difference between 20 and 10 is 10.

So that means that Aisha picked up 10 more pieces of litter than Andeep.

Well done if you got that one.

B, how many fewer pieces of litter did Sam pick up than Jun? Sam picked up nine pieces and Jun picked up 18 pieces.

Remember, the larger number goes first when we're subtracting to find the difference.

So 18 subtract nine.

Laura knows that this is equal to nine.

The difference between nine and 18 is nine, so we can see that Sam picked up nine fewer pieces of litter than Jun.

Well done to you if you've got that one.

C, what is the difference between Laura's number and Izzy's number? We can see Laura picked up 13 and Izzy picked up 13.

Hmm.

Laura and Izzy picked up the same number of pieces.

We know that a number subtract itself is equal to zero.

So 13 subtract 13 is equal to zero.

So we can say that the difference between Laura's number and Izzy's number is zero because they were equal.

Well done if you've got that one.

And D, what is the difference between Laura's number and Sam's number? Laura picked up 13 pieces and Sam picked up nine pieces.

This will bridge through 10, but the numbers are close together so we can always use our counting on strategy.

13 subtract nine is equal to four because four more than nine is 13.

We can see that on our scale that the difference between 13 and nine is four.

So we can say that the difference between Laura's number and Sam's number was four.

Well done if you got that one and well done for completing B.

Let's have a look at what we've covered today.

A bar chart is a graph that uses bars to represent information.

Bar charts can have different scales.

The difference is one of the parts that make our whole, the whole subtract the part is equal to the other part, which is the difference.

You can calculate the difference by counting on from the known part to the whole.

Thank you for joining me today.

I can't wait to see you all again soon to continue our learning.

Goodbye.