Lesson video

Hello, scientists.

My name is Mr. Wilshire.

In this lesson, we are going to be looking at how scientists work.

The outcome for this lesson is I can describe how some scientists control variables and why some scientists do not.

There are some key words to consider as we work our way through this lesson.

The first is variables.

Next, control.

After that microorganism, then antiseptic.

Finally, astronomer.

You may have heard some of these words before or know what some of them mean.

Don't worry if you're not too sure because you can pause a video here and recap.

Restart the video when you're ready to move on.

The first part of this lesson is called materials scientists control variables.

Andeep and Sam have been learning about materials and how they can be changed.

Andeep says, "I'm really interested in learning about materials." Sam says, "Oh, me too.

I wonder what types of scientists work with materials?" Excellent question.

I wonder who? Laura says, "Well, some scientists study what happens when materials change state.

Others help to develop new materials." Lucas then says, "A materials scientist studies the properties of materials.

They carry out research and create or improve materials." I wonder if you know of any other careers that could involve the study of materials.

Have a discussion here and pause the video.

Restart when you've done that.

How did you get on? I wonder if you were able to name any different types of careers.

What about somebody who works building a submarine? An engineer, for example, they would need to know the exact type of materials that they need to make everybody safe in the submarine under the water.

They wouldn't want it to go wrong, would they? Scientists who investigate materials often control, measure, and change variables.

In a comparative or a fair test investigation, scientists only change one variable to observe or measure its effect on another variable.

This scientist studies the transparency of different materials.

They are a material scientist.

She says, "I can change the material and then measure the amount of light that passes through it." All other variables must be controlled.

Control variables are variables that are kept the same throughout an investigation.

The material scientist continues, "when investigating how transparent different materials are, I need to control variables such as the size and the thickness of the material, the brightness of the torch used and the distance of the torch from the material for each test." So she needs to think about all the different things that are gonna happen during this experiment so she can work out the best type of material to use to be transparent.

Let's stop and think.

Scientists who investigate materials will often control, measure and change variance, variables or varyings.

The correct answer here is variables.

Scientists who investigate materials often control, measure, and change variables.

Now, here's another material scientists and they've got a question.

My question is, they say, how does the volume of water affect the amount of sugar that can dissolve in it? In my investigation, I will only change one variable, the volume of water.

This will help me to find out the effects that only one variable has on the amount of sugar that dissolves.

Important control variables that this investigation are the type of sugar cube, the size of sugar cube, the number of sugar cubes, the size of the beaker, the material of the beaker, the temperature of the water, the temperature of the room, and the number of stirs.

Wow, there's a lot of different control variables needed there.

So this is the test.

To make it fair, they're going to use the same amount of sugar.

They're going to use identical beakers containing different volumes of water.

So the only thing that's changing here is the volume of water.

They can't change the sugar between each one.

They're just going to change the amount of water in each of the identical beakers.

The scientist and continues, they say, "By changing any one variable and making sure to control any others, I can be confident that the volume of water was the only variable that affected the amount of sugar that dissolved in it." Let's stop and think on that now.

What happens to control variables in an investigation? They're changed, they're not included, or they're kept the same.

The correct answer here is that they are kept the same.

Here is task A.

Here is a question that a material scientist might ask.

They say, which material melts at the highest temperature? This comparative test investigation, you're going to need to know one, which variable you could change? Two, which variable you're going to measure? And three, which variables you are going to control? Have a go at completing that task.

Restart when you're ready to move on.

How did it goes on? Well, the question, which material melts at the highest temperature could have been answered like this.

The variable that you're going to change is the material.

The variable that you'll measure is the temperature at which the material starts to melt, and the variables that you'll control will be the size and the thickness of the material and the distance of the material from the heat source.

All of those things are variables that you'll need to consider.

I wonder if you thought of the same or if you've been able to think of any more.

Well done.

The next part of this lesson is called, some variables cannot be controlled.

Joseph Lister was a British surgeon and a scientist who worked in the 19th century.

At that time, he was shocked to discover that a lot of people died after surgery.

Lister thought that this might be due to infections from things called microorganisms. Microorganisms are very tiny living things like bacteria or fungi.

You can't see them only with a microscope.

Here is a microscopic image of some bacteria, and here is a microscopic image of some fungi as it's growing.

Lister was very interested in what variables affected the survival rate of patients after surgery.

He wanted to know if patients had a better chance of survival when medical staff involved in the surgery washed their hands to remove harmful microorganisms. Now, this might seem pretty much common knowledge to your eye.

We know that to keep ourselves healthy, we should make sure that we wash our hands, but back then this wasn't as well known and people weren't as hygienic as we are now.

So think about this now, which variable is he going to change and which variable is he going to observe? Pause the video and discuss.

Restart when you've done that.

How did you get on? Have you thought about the variable that you're going to change and the variable that was going to be observed here? Well, the variable that he decided to change is whether medical staff washed their hands.

The variable that he'll observe is the survival rate of patients.

Hmm, that doesn't really seem like a nice thing to measure, does it? Joseph Lister here says, "I'd like to keep the same patient for each surgery, so I can observe if they survive depending on if the medical staff washed their hands or not.

I wouldn't want to volunteer to be one of his patients.

Would it be possible for Lister to control this variable each time though? Hmm.

Have a think and discuss.

Restart when you've done that.

So what do you think? Is it gonna be possible for Lister to control this? Well, there are some types of investigations where some, but not all variables can be controlled.

Lister would not have been able to repeat the same surgery on the same patient each time.

He would've had to have used different patients who could have been men or women of different ages, heights, and health backgrounds.

Therefore, the patient was a variable that he wasn't able to control in this investigation.

Also, I think it would be very, very hard to get anyone to volunteer to see whether they're going to survive or not.

I don't think I'd volunteer.

Stop and think which people here is correct.

Is Laura, correct? All variables must be controlled in every type of investigation or Lucas here, in some types of investigations, not all of the variables can be controlled.

Who do you agree with? Well, I think I agree with Lucas more here.

In some types of invest investigations, not all of the variables can be controlled like the patients that were used in Lister investigations.

Now, Lister also investigated some of the other variables as well, including whether cleaning the instrument used in surgery, the operating room, or the patient's wounds after surgery affected the survival rate of patients.

Here you can see some surgical instruments.

Now, I dunno about you, but surgical instruments that we use nowadays look a lot cleaner and shinier than that, don't they? Lister observe that washing hands and cleaning to remove harmful microorganisms, improve the survival rate of patients.

Oh, well, I'm sure am glad that he was able to come to that conclusion.

It probably means that doctors, nurses, and other staff in hospitals are a lot cleaner nowadays.

Joseph Lister's findings led him to develop antiseptics.

Here, as an example of some antiseptic spray.

You may have seen something like this before.

Antiseptics prevent the growth of microorganisms. They're used to keep wounds clean.

Antiseptics are still used today to reduce the risk of infection and stop the spread of infectious diseases.

Let's stop and think, which scientists undertook scientific investigations that led to the development of antiseptics? Was it Louis Pasteur, Joseph Lister, Dorothy Hodgkin, or Marie Curie? The correct answer here is Joseph Lister.

He is the one who undertook scientific investigations that led to the development of antiseptics.

Now, Sarah Gilbert is a British scientist.

She was born in 1962.

Here, is a picture of Sarah Gilbert.

She studies and develops vaccines to help prevent the spread of infectious diseases.

Her recent scientific work has had a huge impact on public health.

Gilbert's work resulted in the development of a COVID-19 vaccine in the year 2020.

Here you can see the COVID-19 virus that was taken under a microscope.

Now in her work, some of the variables that Gilbert may have controlled include; the ingredients in the vaccine, the amount of vaccine given, where the vaccine was stored and the temperature the vaccine was stored at.

All of these things here needed to be considered in developing the vaccine, and Sarah Gilbert is the one who is able to help save a lot of people's lives after this vaccine was administered.

Let's stop and think, Sarah Gilbert's vaccine helped limit the spread of which of the following viruses? Influenza, rhinovirus, virus, COVID-19, or measles.

The correct answer here is COVID-19.

Here is Task B.

Think about the important work carried out by Sarah Gilbert to develop a COVID-19 vaccine.

As with William Lister's investigations, Sarah Gilbert and her team could control some, but not all variables.

Why do you think that Gilbert and her team were not able to control the variable, the patient who tested the vaccine? Talk to a partner about your ideas and restart the video when you're ready to move on.

I wonder what you answered and whether it was similar to this.

I think this because each vaccine wouldn't be tested on the same patient.

The patients would be men or women of different ages, heights, and health backgrounds just like Listers, so that's something that could not be controlled.

The last part of this lesson is called, observing space.

Astronomers study the night sky, including stars and planets.

They learn more about how our universe works by making observations and looking for patterns in their data.

However, astronomers cannot control variables in space.

Hmm.

What does that mean? Well, astronomers make measurements or observations to explore situations where there are variables that they can't control.

As they can't control or change the variables that they're studying, they answer questions by looking for possible links, patterns, or connections using their observations.

Here you can see an astronomer observing some star maps and also mapping out some real pictures taken by satellites of the Moon there.

Let's stop and think.

Astronomers are able to control variables.

Is that true or false? The answer here is false.

Can we justify our answer? Read those statements and match.

The correct answer here is A, astronomers make observations and look for patterns in their data, but cannot control variables in space.

Nicholas Copernicus was born in 1473 in Poland.

He was the very first astronomer to suggest that the Sun is the very centre of our universe.

Here you can see a diagram of the solar system with the Sun in the exact centre.

Now until his work, other scientists like Aristotle had thought that actually the Earth was the centre of the universe and that the Sun of all the other planets orbit Earth.

Copernicus made observations of the planets to see how they moved in the sky.

There you can see statue of Copernicus.

He used a telescope for his observations and mathematical calculations to help him explain what he observed.

His observations provided evidence to support his idea that the Sun is at the centre of the universe.

Maggie Aderin-Pocock is a British space scientist born in 1968.

Here is a picture of Maggie.

She designs and builds instruments that are carried on satellites in space.

Wow.

What an amazing job.

She uses these instruments to make scientific investigations.

As a space scientist, Aderin-Pocock tries to learn about our universe and help other people to understand it.

The work of astronomers helps us understand how planets, including Earth, formed and are continuing to develop.

Aderin Pocock's work in particular helps us understand Earth's climate and track climate change.

Stop and think, how does the space scientist, Maggie Aderin-Pocock make her observations? Is it by using instruments on microscopes in space? Is it using instruments on satellites in space or using instruments on rockets in space? The correct answer here is using instruments on satellites in space.

Here is task C.

Here is a question an astronomer might ask.

Does the size of an asteroid affect the size of the crater it makes on the Moon? Which variables would an astronomer not be able to control to answer this question? Hmm.

Have a good think and discuss.

Restart when you're ready to move on.

How did you get on? Were you able to think about some things that the astronomer won't be able to control? Well, your answer may have included some of these ideas.

Astronomers cannot predict exactly when asteroids will be close enough to hit the Moon or which part of the Moon that they're going to hit.

They cannot control the size or the mass of the asteroids or what they're made of.

They also can't control how fast the asteroids will hit the Moon or how they might break apart during the collision.

This is why astronomers rely on their observations of space to answer questions.

Lots of different ideas there.

Lots of things that they really can't control.

I didn't even think about the mass of the asteroid or the material it was made of.

Different asteroids are obviously made out of lots of different things.

Let's summarise our lesson.

Scientists who investigate materials often control, measure, and change variables.

Control variables are variables that are kept the same throughout an investigation.

There are some types of investigations where some, but not all, variables can be controlled.

Astronomers make observations and look for patterns in their data.

However, they cannot control variables in space.

Well done for completing that task and hopefully that's given you an insight into the very important work that scientists do.

It may even inspire you to create some of your own satellites that might go into space in the future.

I'm Mr. Wilshire.

Thank you very much for listening.