Hello, my name is Mrs. Mehrin and I'm so excited to be learning with you today.

Today we are going to be learning all about water resistance and we are going to be doing and reviewing.

Welcome to today's lesson from the unit forces, including simple machines.

Your learning outcome for today is I can carry out an investigation into water resistance and evaluate results.

Here are your keywords for today.

Now, you don't need to write these down because I will be going back over them throughout the lesson.

However, if you'd like to, you can pause the video here and jot them down.

And here are the definitions for those words.

Again, you don't need to pause the video if you don't want to because I will be going back over these definitions throughout the lesson.

But if you'd like to write these down, you can pause the video here.

Off you go.

Fantastic.

Well done.

So your lesson today is split into three sections.

Let's begin with the first one, which is investigating water resistance.

So Andeep is investigating how shape affects the force of water resistance.

And Andeep says, "Does the shape of an object affect water resistance?" He plans to make differently shaped pieces of modelling dough.

Then he'll measure the time it takes to fall through a big bottle of water.

How could Andeep measure this? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic.

Well done.

So Andeep could count number of seconds in his head.

He could use a sand timer like the one in the picture.

He could count the seconds on a clock, he could use a stopwatch.

Now, scientists have to plan how they will make their measurements and they sometimes have to choose from a range of scientific equipment.

Which of Andeep's methods would you choose and why? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic.

Well done.

So the stopwatch would be the best one for Andeep to use.

Now, if we count in our heads, we might not always count at the same speed.

So sometimes you may count a little bit faster than another time or you may count slower.

Sand time is only useful for measuring a particular amount of time.

So say, for example, a minute or 10 minutes.

And the second hand on clocks is possible, but you can lose track of where you started.

However, stopwatches, they allow you to measure time accurately even when there is less than a second difference between measurements.

Now, Andeep sets up his investigation to answer his question, which was does the shape of an object affect water resistance? So here we have bottles, we've got a two-liter bottle with the top cutoff, we've got water and we've got the shape that Andeep made using modelling dough and he plans to time how long it's going to take for each shape to fall to the bottom of the water bottle.

Would you set up your investigation like this or do you have any other ideas about how you may set up your investigation? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

So you may have had other ideas.

However, that is the way that Andeep is going to do it.

So it says here match the measuring equipment to what it would measure.

So we've got scales, we've got a ruler, a stopwatch, and a newton metre.

So does the scales measure force or time or length or mass? And I want you to ask yourself that question for each of the pieces of equipment and see if you can match them up.

I'll give you five seconds to think about your answer, but if you do need more time for this question, you can pause the video here and you can come back.

Off you go.

Fantastic.

Well done.

Let's see if you were correct.

So the scales would go with mass.

They measure mass.

Rulers measure length.

Stopwatches measure time, and newton metres measure force.

So starting with the least accurate and ending with the most accurate, order these ways of measuring time.

So you've got stopwatch, counting in your head or clock.

So you're going to start with the one that's the least accurate and then you're going to end with the one that is the most accurate.

So I'd like you to pause the video here and have a go at that activity.

Off you go.

Fantastic.

Well done.

Let's see if you are correct.

So the least accurate would be to count in your head because as we said, you may go too quick or you may go slower.

So it's not very accurate at all.

With a clock, you may end up not remembering where you started, losing track of time.

So again, it's not the most accurate.

And finally, the most accurate is the stopwatch because it will give you that time right down to the milliseconds So we are going to be carrying out our investigation to explore how the shape of an object affects water resistance.

So you might follow Andeep's method or you might have had your own ideas.

So you can make the piece of playdough into different shapes and you can drop each one in the water and time how long it takes to reach the bottom.

So remember, you're going to need your stopwatch to do that.

And then I want you to record your results in a table.

So I'm going to give you some time now to have a go at that.

I'd like you to pause the video here because it might take you some time to do it.

So pause the video here and have a go at that activity.

Off you go.

Fantastic, well done.

So your shapes may have been a ball, a sausage, it may have been flat and this is what your results table should have looked like.

So you've got your time to drop right to the very bottom of the bottle and you've got your three shapes there.

So we can see that the ball took 0.

75 seconds.

So less than a second, each of them took less than a second to fall down to the bottom of the bottle.

Now, I can see by looking at these results that the flat shape took the longest to reach the bottom, but the sausage shape was the fastest.

Here is our next part of our learning then today.

It's scientists repeat investigations.

So these are Andeep's results.

Were your results like Andeep's results.

And do you think Andeep's results show clearly which shape took longer to fall? I'd like you to have a think about those questions.

I'd like you to pause the video here so you can have a really good think.

Off you go.

Fantastic, well done.

Now, the next question I want you to think about is do you trust the results ofAndeep's investigation? If yes, why? And if no, why not? I'd like you to pause the video here and have a really good think about that question.

Off you go.

Fantastic.

Well done.

So Andeep realises that he cannot use his results to answer his inquiry question.

The shapes fell so quickly through the liquid that it was difficult to time them accurately and he doesn't trust his results.

Now, sometimes scientists record results, which they know they cannot rely on or trust to answer their questions.

And this doesn't mean that they have done something wrong, but it might mean that the results are unreliable.

It means they have to think of a different, more reliable way of making their measurements.

So have a little think, what could Andeep do to measure the time more reliably? I'll give you five seconds to think about your answer or you can pause the video here if you need longer.

Off you go.

Fantastic.

Well done.

So Andeep decides that he's going to film the shapes falling through the water and he's going to use the slow mo setting on the camera.

This is going to allow him to compare the time more accurately.

Did you have any other ideas apart from doing this method that Andeep had? I'll give you five seconds to think about your answer or if you need longer, you can pause the video here.

Fantastic, well done.

So some of the ideas that you might have thought of was possibly using a thicker clear liquid so it takes longer for those shapes to fall through to the bottom or even using a larger volume of liquid to fall through.

So you may have had a bigger bottle, for example.

So there's a lot more water, there's a lot more volume of water and it takes longer for those shapes to fall through.

So he also decides that he's going to take three repeat measurements for each shape.

So he's got three balls, three sausages, and three flat shapes.

And this is going to make his results more reliable and he's going to be more confident that he can trust them.

Now, let's do a quick check-in of your learning so far.

Why is it difficult to measure short times accurately? Is it because A, the numbers on stopwatches are too hard to read when you get to decimal places? Is it B, it can be hard to press the button on the stopwatch at exactly the right time, or is it C, sometimes stopwatches don't show accurate numbers? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

The answer was B, it can be hard to press the button on the stopwatch at exactly the right time.

So let's have a look at another question.

It says why does taking repeat measurements help scientists trust their results? Is it A, it means the table of data looks more scientific? B, it shows how much data can vary.

Or C, any incorrect readings should stand out.

Have a go at that question.

I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic, well done.

The answer is B and C.

It shows how much data can vary, but it also allows you to see any incorrect readings because they stand out straight away.

So I want you to have another go at the investigation from task A.

And this time, I'd like you to film the shapes falling using the slow motion setting on the camera.

So it may be called slow mo on your camera.

Now, watch the film and measure the time it takes for each shape to fall to the bottom.

And I want you to repeat this three times for every shape and record your results in a table like the one you did for task A.

So pause the video here and have a go at that activity.

Off you go.

Fantastic, well done.

So here are Andeep's results.

So we can see now that the time that it's taken is much larger and it makes it a lot more obvious to see which one has fallen through the quickest and which one has taken the most time.

So we can see here that for the ball, it was on average three, almost four seconds.

So that was the fastest.

We can see that the sausage took the next longest to fall through whereas actually in task A, the sausage was the fastest and we can see that the flat shape took much longer, more than double the sausage shape.

So the time you measured from the film has helped you to compare the different shapes.

But remember that is not the real time taken because it's a measurement of slow motion time.

So here is our last part of our lesson today, which is scientists evaluate investigations.

So Andeep looks through his new set of results and they are much easier to trust and compare now and much more reliable.

And now he can answer his question and make a conclusion.

So in a conclusion, scientists explain what the results show or what they mean.

So what do Andeep's results show us then? I'll give you some time now.

I'd like you to pause the video and have a really good look at his results.

What are his results showing us? I'd like to pause the video here and have a go.

Fantastic.

Well done.

So Andeep's results show that the ball shape fell faster than the sausage shape and the sausage shape fell faster than the flat shape.

What does this tell him about the water resistance of different shapes then? I'd like you to pause the video here and see if you can answer Andeep's original question about whether or not different shapes were affected by water resistance differently.

Pause the video here and have a go.

Off you go.

Fantastic.

Well done.

So Andeep knows that water resistance slows down objects.

The greater the water resistance, the more an object will be slowed down.

So Andeep says the slowest shape, the flat one, had the greatest water resistance than the sausage shape and the ball shape had the least water resistance.

So we can see the arrow is showing us that it's decreasing in water resistance.

Andeep tries to link his conclusion to the surface area of the shapes.

And so we can see here where you have an increased surface area, it seemed to have taken longer.

And he says, "I think that greater surface area can increase water resistance." So let's have a look at this question here.

It says which statement is true about different shapes falling through liquid? Is it A, the slower shape has the least water resistance? B, greater surface area can increase water resistance.

Or C, greater surface area can decrease water resistance.

I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic.

Well done.

The answer is the greater surface area can increase water resistance.

Now, scientists also make evaluations about their conclusions.

The evaluation includes how reliable they think their results are.

And Andeep knew that he could not trust his first set of results from task A.

Can he trust these results? I'd like you to have a really good think about that.

I'll give you five seconds or you can pause the video here.

Off you go.

So now I want you to think about these two questions.

Do you think that these results are reliable and how do you know that they're reliable? Have a think about that question.

If you need to, you can pause the video here or I'll give you five seconds.

Fantastic, well done.

So this is what Andeep writes in his evaluation.

He says, "I think the results were reliable because I took each measurement three times and the time I measured was similar for each one.

Also, on the slow motion film, there was a clear difference in the times taken for the three different shapes.

It was easy to tell them apart.

Let's see if you can fill in the blanks for these statements here.

So it says in the something, scientists explain what the results show and answer the inquiry question.

In the something, scientists explain whether they trust their results.

So I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

So in the conclusion, scientists explain what the results show and answer the inquiry question.

In the evaluation, scientists explain whether they trust their results.

Let's have another check of your understanding.

It says match the statement to the part of the investigation in which it should appear.

The flat shape had the greatest water resistance.

Should that be an evaluation, conclusion or results? I know the results were reliable because we took repeat measurements and they were similar each time.

Should that be in the evaluation, the conclusion or the results? And the last one, the flat shape took 9.

87 seconds to fall through the water.

Should that be in the evaluation, the conclusion or the results? I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic.

Well done.

Let's see if you were correct.

So the flat shape had the greatest water resistance should be in the conclusion.

The second one, I know the results were reliable because we took repeat measurements and they were similar each time should be in the evaluation.

And the flat shape took 9.

87 seconds to fall through water should be in the results.

So let's take a look at our results for task B.

It says use them to help you write a conclusion and evaluation.

So remember to include an explanation of the results.

So what do they show you and why did it happen? And of your degree of trust in the results, do you think they're reliable and why? So I'd like you to pause the video here and have a go at doing your conclusion and evaluation.

Off you go.

Fantastic.

Well done.

So you might have written something like this.

Our results show that the ball shape fell fastest and the plate shape the slowest with the cube shape in between the two.

The ball shape had the least water resistance.

So it must have had the smallest surface area for water to push against.

The plate shape had the greatest surface area and water resistance so it was slowed down the most.

And your evaluation may say, I think the results were reliable because I took each measurement three times and the time I measured was similar for each.

All of the times for the plate shape was slower than for any other shape.

So let's have a look at our summary for today's lesson.

It says sometimes scientists have to choose between a range of equipment for their investigations.

Scientists can take repeat measurements to make sure that they are reliable.

The evaluation of an investigation can include an explanation of and degree of trust in the results.

Objects with greater surface areas have greater water resistance because there is a greater area for water to bump into.

Fantastic learning today.

I am so proud of you.

I know there has been so many new things for us to learn, but you have done brilliantly.

Well done.