Hi, everyone.

It is lovely to be learning science with you today.

I'm Dr.

Pemberton, and I'm really looking forward to working through the lesson, so let's get going.

Today's lesson is called Friction: Do and Review.

We'll improve our understanding of friction by carrying out an investigation, and reviewing our results.

The learning outcome for today is that you can carry out an investigation into friction, and evaluate the results.

It's part of our big question, how do forces make things happen? I'm looking forward to doing some practical work today, and to learning a bit more about evaluating results.

I hope you are too.

These are the keywords that we'll be using in today's lesson.

Surface, friction, variables, and conclusion.

Do you know any of them already? This slide shows the meaning of each of the keywords.

We won't spend time going through each one now because I'll explain them as we come across each of them during the lesson.

However, the slides here is a reminder, and you might like to come back to it later to check that you have understood each of the words.

This is our lesson outline for today.

There are three parts to it.

The first part is comparing friction on different surfaces, then we will learn about presenting results, and finally, we'll consider why and how scientists make conclusions.

We're going to start now with friction acts between surfaces.

This is our lesson outline for today.

There are three parts to it.

This is our lesson outline for today.

There are three parts to it.

The first part is comparing friction on different surfaces, then we'll learn about presenting results, and finally, we'll consider why and how scientists make conclusions.

We're going to start now with comparing friction on different surfaces.

Friction is the force between two surfaces that are moving or trying to move across each other.

In this picture, the diagram shows a red box on a blue surface.

If the box is moving over the surface, the area where the friction occurs is shown in white.

You can see the red and blue surfaces are not completely smooth.

Bits of them stick out and make contact with each other.

Scientists carry out investigations to measure and compare how different surfaces have different amounts of friction.

How could you measure the friction created by different surfaces? You can use a force metre to measure the force needed to move an object over different surfaces.

This is a force metre in this photo.

You can attach objects to the hook at the bottom, and the force they exert pulls the marker down the scale by stretching a spring.

The marker shows you how much force is being used.

The greater the force needed to move the object over a surface, the greater the friction of that surface.

"Aisha has set up a fair test investigation to compare the friction created by different surfaces in her school.

Her inquiry question is, do different surfaces create different amounts of friction?" Oh, that's a good question because it can be answered with an investigation, so it's a scientific question.

"Aisha plans to compare the friction force needed to pull a weighted shoe over different surfaces." And we can see a diagram of what she plans.

There's a red shoe with a one kilogramme mass in it.

She's added the mass because the shoe would be too light otherwise, and it would hardly require any force to pull it over any surface.

This mass will make it a bit harder, but it's still a fair test because she'll have the same mass in the shoe for every surface she tests.

We can also see that Aisha has hooked the force metre into the shoe, and she plans to pull on this to move the shoe.

The only variable she will change is the surface.

Aisha decides to record the results of her investigation using a table.

She needs to think about what will go in her table.

First, she decides what the column headings will be.

They are surface on the left hand column, and on the right hand column, she's written force needed to pull the shoe.

Newtons.

Ah, in the column heading, she's made sure that she's included the unit of measurement so she doesn't need to write it in for each number.

Finally, she writes down the surfaces she will test.

She's chosen lino.

That's the surface of her classroom floor, Wood, carpet, grass, and tarmac.

She'll use the grass on the school field, and the tarmac on the school playground.

Aisha is now ready to collect data, and we're ready to see what we've learned so far.

Let's check by trying a couple of questions.

This is a missing word question.

I'll read it out and say blank where the missing word should go.

Blank is the force between two surfaces that are moving, or trying to move across each other.

Ah, the answer is friction.

Friction is the force between two surfaces that are moving, or trying to move across each other.

Let's try another one.

This one's a multiple choice question.

What does friction do to moving objects? It A, speeds them up, B, slows them down, or C, nothing.

That's right, it's B.

Friction slows down moving objects.

Now it's time for your first task.

In this task, you're going to carry out Aisha's investigation to answer the question, do different surfaces create different amounts of friction? You could use Aisha's method like this.

Put a one kilogramme weight in a shoe, and hook a force metre onto the shoe.

Pull the shoe over a surface as smoothly as you can, and measure how many Newtons this takes.

Record your results in a table, then repeat this on different surfaces.

The only variable you are changing is the surface.

You're controlling the other variables.

Before you start trying to measure, I really recommend that you have a few gos pulling the weighted shoe with the force metre because it can take a little bit of practise to do this smoothly, and if you don't do it smoothly, you don't get a good reading.

Pause the video now while you go and do your investigation, then come and rejoin me for the rest of the lesson.

How did you get on? Your results might have looked like this.

You can see that in these results, the force needed to pull the shoe over the lino was four Newtons.

For wood, it was five Newtons, carpet was 9.

5 newtons, the grass was 14 newtons, and finally nine Newtons were needed to pull the weighted shoe over the tarmac.

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

In this section, we're learning about presenting results.

While scientists are carrying out their investigations, it's often easiest to record numbers or measurements in a table.

After the investigation, they can present them as graphs.

Graphs are a way of showing results as a type of picture or diagram, rather than just a list of numbers.

You can see data presented in two different graphs in the picture on the right.

Sometimes results are easier to understand if they are presented in this way because it's easier to see patterns.

Some of the graphs that scientists can use are bar graphs, which are sometimes called bar charts, but they mean the same thing.

This one shows how children in class five travel to school.

I know that because it says so in the graph title, and I can see that the choices for the transport for travelling to school were car, bike, walk, or bus.

Another type of graph is a scatter graph, and I can read this title to see that this one shows how height compared to weight in a group of 18 year olds, and another type of graph is a line graph.

Here we can see a line graph showing how temperature changes over the course of the day from 7:00 AM to 9:00 PM, or 2100 hours as it says on this graph.

They've used the 24 hour clock.

There's different types of graph as you can see, and different types of graph are good for showing different things.

We're only going to think about bar graphs today.

Bar graphs are really good for showing data that can be grouped into clear categories.

This is the bar graph showing how children in class five travel to school.

What are the categories in this graph? Can you remember? The categories are the types of transport.

Car, bike, walk, and bus.

Let's look a bit more carefully at what a bar graph needs.

All graphs have a horizontal line called the X axis.

You can see it highlighted in the yellow here, and they also have a vertical line called the Y axis.

The numbers or measurements go on the Y axis.

Here the Y axis is used to show the number of children using each type of transport.

A scale is drawn up the Y axis.

The numbers must be spread evenly on the scale so that the gap between each number is worth the same amount each time.

And the categories are listed on the X axis.

Finally, each axis needs a label to show what the data means, and the graph needs a title.

The next step is to add the data.

To put the data in the graph, you draw a bar from the bottom line up until it's level with the correct number on the Y axis.

So for the car category, I drew a bar up until it was level with number seven on the Y axis.

For bike, it was number two, for walking, all the way up to number seven again, and for the bus, the bar just went up to number one.

Now I said you go up to the correct number.

The correct number is the number recorded in the table when you collected the data, just like you can see here.

People often colour in bar graphs to make them easier to understand.

Okay, it's time to see what you can remember about graphs with a couple of questions.

This is a multiple choice question.

Which type of graphs are good for showing data which falls into clear categories? Is it A, scatter graphs, B, bar charts, or C, line graphs? That's right, it's B.

Bar charts or bar graphs are good for showing data which falls into clear categories.

Well done if you've got that.

Let's try another one.

This is another multiple choice question.

Why might scientists present their results as graphs? Is it A, because the bright colours make the work look more interesting? B, because they can be easier to understand than a list of numbers? Or C, because they can reveal patterns clearly.

That's right, it's B and C.

Graphs are good at making data easy to understand, and they can reveal patterns clearly.

Now it's time for you to do some more science.

You are going to create a bar graph to present your data from Task A.

There are a few things you need to do before you begin.

The first of these is to make sure your pencil is sharp, and that you have a ruler.

Always use these when you're making a graph.

Then you need to make some decisions.

Decide which data will go on the X axis, and which will go on the Y axis.

So, what are your categories? You also need to decide what range of numbers you should have on your Y axis.

That means decide what the lowest number at the bottom of the graph should be, and what the highest number at the top should be.

You'll need to know your smallest and largest numbers to be able to decide this.

Pause the video now while you make your graph, and then come and rejoin me to carry on with the rest of the lesson.

Welcome back.

How did you get on? I wonder if your graph looks like this.

Aisha has labelled the X axis surface, and has written down the names of each of the surfaces.

The different surfaces are her categories.

The Y axis is labelled force and has an N in brackets after it to show that the units are Newtons, and she's coloured her bar in blue.

We'll come back to our graphs later, but now we're gonna move on to our third and final section today.

It's called scientists make conclusions.

The findings from an investigation can be summarised into a conclusion.

To do this, scientists need to make sense of their findings and answer the inquiry question.

They also try to explain why the results show what they do by linking them to their existing science knowledge, or to their ideas about science.

These are Aisha's results again.

What should her conclusion be? Aisha can see that it took the lowest number of Newtons to pull the shoe over the classroom floor that was lino.

She concludes that the lino floor created the least friction of all the surfaces she tested.

So, she knows what the data show.

Can we help her try to explain why she got these results, and link it back to the science? Aisha thinks back to her original inquiry question, do different surfaces create different amounts of friction? This is her conclusion.

The different surfaces do create different amounts of friction.

The lino created the least friction, and the grass created the most.

This is because rough surfaces tend to create more friction than smooth surfaces.

<v ->The grass was the roughest surface,</v> and the lino was the smoothest.

This is a good conclusion because Aisha's used her understanding of friction on rough and smooth surfaces to help explain her own results.

While she's been doing her investigation, Aisha has made an observation.

Aisha spotted that all the classrooms have got lino floors, but they're not all the same types of lino.

Aisha's results and observations have helped her come up with a new question to investigate.

She now asks, do all types of lino create the same amount of friction? Sometimes, test results help scientists to make a prediction for further investigation.

So Aisha's results and observations helped her come up with a new inquiry question.

Do all types of lino create the same amount of friction? Using Aisha's results, what would you predict and why? Aisha predicts that smoother lino will have less friction than rough lino because when she tested the other surfaces, smoother surfaces generally created less friction.

Let's check what we can remember with some questions.

The first is a multiple choice question.

Which two of these would you find in a conclusion? A, a graph, B, a summary of the findings, C, an answer to the inquiry question, or D, a prediction? That's right, it's B and C.

You'd find a summary of the findings and an answer to the inquiry question in the conclusion.

Let's try another one.

Here we have some results.

What would you include from this inquiry question and graph? The question is, in class five, which is the least popular type of transport used to come to school? Is it A, car, B, bike, C, walk, or D, bus? That's right, it's D, the bus.

I can see this is the lowest bar on the graph.

Now it's time for you to do some more science.

This task has two parts.

For the first part, you need to use the results from task B to write your conclusion in response to the inquiry question, do all surfaces create the same amount of friction? In the conclusion, you should explain how the results support your decision.

For the second part of the task, think of another question to investigate about friction.

Use your results from the first part to help you make a prediction about what you think will happen.

Pause the video now while you do this, then come and rejoin me to carry on with the final bit of the lesson.

Welcome back.

If this graph showed the results, then your conclusion may have looked like this.

Different surfaces created different amounts of friction.

The wood created the least friction, and the carpet created the most.

This is because rough surfaces tend to create more friction than smooth surfaces.

The carpet was very thick so it had the roughest surface, and the wood was really polished so it had the smoothest.

The second part of your task was to come up with a further question and prediction.

You may have come up with something like this.

My house has lots of different rugs and carpets, and they're all different thicknesses.

Do the different rugs and carpets create different amounts of friction? I predict that the thicker it is, the greater the friction it will create.

Well, we're nearly at the end of our lesson.

Let's look at the summary to remind ourselves what we have learned.

Rough surfaces tend to have more friction than smooth surfaces.

Scientists carry out investigations to measure and compare the friction of different surfaces.

The results from an investigation can be recorded in different ways, including tables and graphs.

The findings from an investigation can be summarised in a conclusion, and finally, test results can be used to make predictions to set up further investigations.

Thank you for joining me this lesson.

I've really enjoyed investigating friction with you, and I hope you have too.

Well done for your hard work, and have a great day.

See you next time.